# Sticky  18s v. 17s?



## Paisan (Dec 4, 2005)

Ok guys debating getting the 17s v. 18s on my new GTO. What's the deal with them? Why are the 18s only 235 v. 245 on the 17s? I'm tempted to get the 17s just cause they are wider.

-mike


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## GM Kid (Mar 21, 2005)

For whatever reason, Holden didn't make the wheel wells particularly roomy. There's only so much tire that'll fit. Think of the wheel well as a room with a vaulted ceiling that peaks in the middle: It gets narrower as you go upward. When you go from a 17" wheel to an 18" wheel, therefore, you have to go to a slightly narrower tire.

I've got the 17s on my GTO, and I'm happy to have the extra 10 millimeters of tread width. Some people like the look of bigger wheels, though--even if it means a narrower tire.

Check out an article in the current edition of Car and Driver in which they test an SLP-modified GTO and Corvette. The mods added 55 horsepower to the GTO, but because SLP also switched to some snazzy-looking 18" chrome rims on Nitto tires, the car was scarcely faster than a bone-stock GTO on 17" rims.


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## Paisan (Dec 4, 2005)

That's what I thought. I wasn't sure if my reasoning was right. So I'm gonna look for the 17" rims since I want more tire in there.

-mike


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## HotRodGuy (Jan 9, 2006)

The width of the 235/40/18's is almost identical to the 245's on the 17's


Going to a 17" wheel won't mean you can stuff a bigger tire in there FYI


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## EEZ GOAT (Jul 9, 2005)

i got 245/40/18 on my goatarty:


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## RedRacer (Sep 12, 2004)

I just put a 245/35/19 in front and a 275/30/19 in the rear. I was hoping not to roll the rear fenders, but I'm going to have to. They rub when I give it 1/2 trottle and the rear end swats. The fender roller is on order and should be here within the next couple of days!!!


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## EEZ GOAT (Jul 9, 2005)

RedRacer said:


> I just put a 245/35/19 in front and a 275/30/19 in the rear. I was hoping not to roll the rear fenders, but I'm going to have to. They rub when I give it 1/2 trottle and the rear end swats. The fender roller is on order and should be here within the next couple of days!!!


why cant a body shop roll a feaken fender. i need to roll mine because if i put adults in the back i better wacht out. how do we roll em


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## EEZ GOAT (Jul 9, 2005)

were are they rubbing at? the inner fender lip, wheel well, or sturt


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## RedRacer (Sep 12, 2004)

EEZ GOAT said:


> why cant a body shop roll a feaken fender. i need to roll mine because if i put adults in the back i better wacht out. how do we roll em


Some can...others won't. Here's the deal... I know that I can do it. I have confidence in myself, but I don't have the confidence in a body shop that I don't know. The price of the tool ($250) is close to the amount a body shop will charge to do the work. I can sell the tool (anyone interested???) and make back most of my money.

Here's a link to the tool that I bought... http://www.eastwoodco.com/jump.jsp?itemID=6159&itemType=PRODUCT

The link give a good picture of what needs to be done.

I only have the fender lip hitting. It is very close to the strut and wheel well, but as far as I can tell, it is only the fender lip. I guess that I'll know more once the fender lips are no longer hitting.


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## 05GOAT (Nov 11, 2004)

Here's some good reading and testing of different size tires. I am running ROH Drift R 18x8 w/ a 245/40/18 tire - 49lbs and ROH Drift R 18x9 w/ a 275/35/18 tire - 51lbs  

Anyhow, I've calculated that if I go with a 245x40 18" tire up front (or 245x35 19") I get the same rolling diameter as stock. But with that I would want to mate it to a wider rear for a little extra meat. In which case, a 275x35 18" (or 275x30 19") would be the closest match, roughly 0.1" shorter than the front.

The catch here is, will a 275x35 mount on an 8" wheel without problems, or will that be an issue? These wheels have a 42mm offset if I remember correctly. Will that in itself be an issue with such a wide rear tire? (with or without rolling the fender lip)

The OTHER option is to go with a 235x40 18" front (or 235x35 19") and a 265x35 18" (or 265x30 19") on the rear which should mount on an 8" wide wheel just fine. This would be a comperable rolling diameter from front to rear but slightly different than stock so the speedo might be off slightly. The drawback here is, these are both very hard to find sizes compared to 245's and 275's.

I remember seeing someone that had mounted 275's on the rear of stock 17x8 GTO wheels and had no problems to speak of, but wondered really what the drawback is going that wide on a narrower wheel and if it was a danger in any way? The simple fact is, I might have to go with the 235's and 265's like it or not, but that'd really limit tire options.

Results of yesterday's wheel & tire test fitting w/ ROH wheels:

Factory wheels & tires:
17x8 w/ 245/45/17
55lbs each (wheel & tire)
5x120mm stud pattern
48mm backspacing

17's
Front: 
245/45/17 is still the best fit
255/40/17 fit but had to use a 8.5" wide wheel, the required backspacing hadthe wheels/tire sticking out too from the body line
275/40/17 didn't fit, using a 9" wide wheel, the tire was rubbibg the strut. Again using a different backspacing would have the set sticking out too far

ROH Drift R 17x8 w/ 245/45/17 - 47lbs
ROH Drift R 17x9 w/275/40/17 - 49lbs

Rear:
275/40/17 fit no problems on a 17x9" wheel
These stick out just a little more than the factory tires, but I think they still look great!

Recommendation for 17" wheels: Use your factory tires and and put them on 17x8" custom wheels or 17x8" wheel front w/ 245/45/17 tires and 17x9" wheel rear w/ 275/40/17 tires

Personally I would just reuse the factory tires and put 17x8" wheels at all four corners. This will be cheaper to do and looks good.

18's
By far the best way to go!!

Front:
18x8 w/ a 245/40/18 tire - fit is perfect
18x8.5 w/ 255/40/18 - again sticks out too far

Rear:
18x9 w/ a 275/35/18 tire - fit is perfect

Recommendation for 18" wheels: Without a doubt the best set is 18x8 up front with 245/45/18 matched with 18x9 out back w/ 275/35/18. This set looks great, fits porportionally and lets you pick up some width out back. The ride quality is also great. Or use 18x8 and 245/40/18 at all four corners.

ROH Drift R 18x8 w/ a 245/40/18 tire - 49lbs
ROH Drift R 18x9 w/ a 275/35/18 tire - 51lbs

19's

Front
245/35/19 on a 19x8" wheel

Rear
275/30/19 on a 19x9" wheel

Recommendation for 19" wheels: GO BACK TO 18"!! While the look great on the car the ride quality is horrible. If you could care less about feeling every bump in the road and want all the look, these are for you. If you just gotta have them then use 19x8 w/ 245/35/19 front and 19x9 w/ 275/35/19 rear or the 19x9 w/ 245/35/19 all the way around.

I have some pics from the fitting I just need to get them off of my disc. I'll get some pics of my Goat with the set up I'm going with and personally recommend,
18x8 w/ 245/4018 front and 18x9 w/ 275/35/18 rear. If I'd been working at Pontiac this is what I would have sold the car with!!

By the way, anyone interested in ROH or other custom wheels contact me I now have pricing and availability info!!

18X8 on front with 245/40's 18X9 on the rear with 275/35 Michelin Pilot Sport AS's
Unfortunately Boyd put a +48 offset on the rears and they rubbed, so I rolled the fenders. Boyd was willing to make another pair but I was tired of waiting. It's been about three months already. I think a +55 would be a perfect offset for these on the rear and Boyd could definately do that.


NEW BOLT PATTERN FOR GENERAL MOTORS 5x120mm

WIDTH OFFSET WIDTH OF TIRE
7.0… +26/+65 215/225/235
7.5 +33/+61 215/225/235/245
8.0 +39/+55 225/235/245
8.5 +45/+48 235/245/255
9.0 (MAX) +48 245/255

REAR ONLY
8.0 +36/+65 245/255
8.5 +42/+65 245/255
9.0 +48/+65 255/265/275
9.5 +55/+64 265/275/285

Offsets greater than shown above will rub on rear fender lip (25mm fender lip).

Another fella posted this: "I have a set of wheels from ROH, the rears are 18x9 51mm 275/35 and front are 18x8 41mm 245/40, with Nittos, no need to roll. BFG or Dunlop you may need to roll?"



The Arrowhead Performance Yellow Jacket 2004 GTO prototype. Thos are Hurst inspired wheels. We got 18x8' rims with 245/40/18 Toyo meats in the front and 18x9' rims with 270/35/18's in the rear. The exhausts exit out each side just before the rear wheels.

Hope this helps.


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## b_a_betterperson (Feb 16, 2005)

Paisan said:


> Ok guys debating getting the 17s v. 18s on my new GTO. What's the deal with them? Why are the 18s only 235 v. 245 on the 17s? I'm tempted to get the 17s just cause they are wider.
> 
> -mike


Awesome post, O5GTO. Your car looks great, too.

Regarding the 235/245 thing -- the factory BFG tires have a square shoulder. If you buy a tire with a rounded shoulder, like the Falken Ziex, you can get more rubber under there. I'm running 2454018s on all four corners -- with no rubbing at all.


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## EEZ GOAT (Jul 9, 2005)

b_a_betterperson said:


> Awesome post, O5GTO. Your car looks great, too.
> 
> Regarding the 235/245 thing -- the factory BFG tires have a square shoulder. If you buy a tire with a rounded shoulder, like the Falken Ziex, you can get more rubber under there. I'm running 2454018s on all four corners -- with no rubbing at all.


do u get passengers in the back? is there any rubbing there?. put i 2 kids in the back and i could not get a finger under the rear fender lip. drove 85 miles home and did not rub but i belive if i get adults back there iam in trouble


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## novacoke (Mar 11, 2006)

Looks aside, what would be the better option? I know next to nothing about tires, but which size would offer the best ride and offer the best traction on snow if the tires were used year round?

Thanks!


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## alptbird (Feb 20, 2006)

*heads up on the rim size!*

this may mean nothing to you but I would maybe make a consideration for it. refer to Yankee's http://www.gtoforum.com/showthread.php?t=6914 might help you deside to go 18's


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## gclcpa (Jan 9, 2005)

*One consideration no one has mentioned*

If you switch from 17s to 18s, you must get the correct size combination so that the height of the tire is the same or very close. Otherwise your speedometer, and I assume your odometer as well, will be inaccurate. The "245" is the width in mm. If you divide by 25.4 you get the width in inches. The "45" means that the height of the tire is 45% of the width of the tire. Therefore, on the stock 17s, the height of the tire is 17" (wheel) + 8.7" (two times the height of the tire (lower and upper height) = 25.7 inches.


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## novacoke (Mar 11, 2006)

Thanks for the input. I saw that thread when it was first posted just after I decided I would go with 18" wheels.. just confirmed my decision when I read that.


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## Stephen Hopkins (Feb 6, 2006)

Something else to consider is that 17" chrome wheels seem (to me atleast) to look smaller on my car than 17" painted wheels with the same tires. It might just be my first impressions since switching to 17" chrome and may go away, but at the moment the 17" chomes look smaller than 17" painted wheels.


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## phantomblackgto (Mar 16, 2006)

Please be aware that there is currently an issue that is showing up, at least with the 17" OEM's, with strut rub on the fronts that is causing serious tire wearing issues. Some have reported finding cords showing after 10K miles. Pontiac (GM) is not acknowledging that any problem exists (surprise!). This is a serious issue. I have reported the issue to the NTSA and would encourage fellow GTO owners to do the same.


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## DrFix2Fly (Oct 27, 2004)

I believe that with the 17" wheel with wider 245mm tires with taller sidewalls will have much more tire flex than the 18" wheel with 235mm tires with the lower profile. In hard cornering the outer wheel's tire will flex in toward the stut causing the rub. This is why 04" owners suffer this problem. My advice is to either use 18's with a lower profile, slightly narrower tires or wheel spacers.


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## Xman (Oct 31, 2004)

I was thinking of using 5mm wheel spacers but think it would be better to replace the existing studs with ones that were also 5mm longer so I still get all the threads needed to keep the wheels torqued right. Adding the spacer should be no different than getting aftermarket wheels with less offset to solve the strut rub issue. Has anyone tried this or know where we can get longer threaded studs?


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## the WRIGHT one! (Jul 19, 2006)

Xman said:


> I was thinking of using 5mm wheel spacers but think it would be better to replace the existing studs with ones that were also 5mm longer so I still get all the threads needed to keep the wheels torqued right. Adding the spacer should be no different than getting aftermarket wheels with less offset to solve the strut rub issue. Has anyone tried this or know where we can get longer threaded studs?


Ebay!


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## mike18228 (Aug 5, 2006)

i have a 2006 m6 wih the stock 18x8 rims and stock tires, what is the biggest size i can put on the rears to get better traction (drag and street)????


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## burnz (Jul 26, 2006)

mike18228 said:


> i have a 2006 m6 wih the stock 18x8 rims and stock tires, what is the biggest size i can put on the rears to get better traction (drag and street)????


dont know the size off hand, but it's more the tier is a summer tire that comes on the stock 18's. I have the 17's those tire stick pretty dam good. they are all season.


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## MSTNGKILLA (Jul 27, 2006)

Great info Man, I have one Question though what would u recommend for the best offset fit for the front and rear?? I will be going with your recommended sizes but what schould I tell my wheel man the offset needs to be .. Thanks for the awsome infoarty:


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## 06GeeTeeOOH (Jul 2, 2006)

i have 19 inch motegi wit fuzion 245/35/19 it looks amazing


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## Tony0131 (Sep 18, 2006)

05goat great info, I was looking for that, I have a 06 GTO and just purchased 18x8's for the front and 18x9's for the rear, from boze alloy. When talking the tech there he said I can go with 245x40x18's for the front and 275x35x18 for the rear and have no problems, it would be the same rolling diameter. I had posted asking this question yesterday but didn't see 05goats post till now. Thanks for the info. Once I receive my weels and get everything on the car I will post pictures.


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## Zebra (Sep 2, 2006)

*Change tire size to eliminate strut rub?*

So, not being a tire man and all. I get confused reading all that aspect ratio junk. In order to eliminate front strut rub could I replace my front tires from 245/45/17 with either:

a) 235/45/17 
b) 245/40/17

Will replacing them with these numbers cause the speedo to be off?
Can I use the same rim if I were to change to one those tires?
I recall seeing a wheel calculator but now I can't find it.


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## Zebra (Sep 2, 2006)

*Will a 235/45/17 seal on 245/45/17?*

OK, after finding and using the tire size calculator at www.miata.net/garage/tirecalcold.html I found that going to a 235/45/17 could eliminate the front strut rub problem. 

However, will it properly seal to the rim??


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## ute (Oct 27, 2006)

Can I run 19x8.5 with a 40mm offset with 245/35/19 fronts and 275/30/19 on rear without major problems???help


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## judgeman6970 (Feb 11, 2007)

*good tire/wheel info....*

great info, 05GOAT.....sounds like u know ur stuff....i will be picking up a '06 with 17" stockers...was thinking of either just replacing wheels(17")...or replacing all with 18"....not racing, so i like the 245/40x18 size all around...which i hope wont rub up-front*_*


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## Xman (Oct 31, 2004)

Xman said:


> I was thinking of using 5mm wheel spacers but think it would be better to replace the existing studs with ones that were also 5mm longer so I still get all the threads needed to keep the wheels torqued right. Adding the spacer should be no different than getting aftermarket wheels with less offset to solve the strut rub issue.


Before I tried any modifications or aftermarket wheels as I was thinking in my prior post, I went and had a wheel alignment done to Pedder's recommendation. I've now have -0.3 degrees camber and a fresh set of 245s on the stock 17 inch wheels. I rotated them last weekend after 5000 miles and had absolutely no indication of strut rub. The only other aspect that has changed other than the alignment to Pedder's recommendation was the addition of SuperPro Poly strut rod bushings. I didn't need the longer studs or taller aftermarket wheels with more offset - just a proper alignment to fix the -1.3 degrees of negative camber the car came with plus the incorrect toe. Sometimes it worth trying the easy less expensive solutions first.


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## HADAWS6 (Dec 5, 2005)

had 17's on my 05 18's on my 06 the 18's look better but dont grip the road , get 17's if u have to winter drive , i am either gonna get a winter car or 17's for the winter .


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## 04stangkiller (Jun 6, 2006)

The reason people want the 18's is obvious visual appeal. I was the same way. then while talkin to a local rim shop owner he described that the 17's rims are smaller in size but the amount of rubber that touches the pavment is more in turn more traction.. that is why i went with the 17's for the winter. able to have more traction and its a heck of a lot better than the nitto 555r on snow with the salt eatin my chromes.. Im polishin up the chromes and storin them in the warmth till spring.


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## gtokid (Feb 21, 2007)

GM Kid said:


> For whatever reason, Holden didn't make the wheel wells particularly roomy. There's only so much tire that'll fit. Think of the wheel well as a room with a vaulted ceiling that peaks in the middle: It gets narrower as you go upward. When you go from a 17" wheel to an 18" wheel, therefore, you have to go to a slightly narrower tire.
> 
> I've got the 17s on my GTO, and I'm happy to have the extra 10 millimeters of tread width. Some people like the look of bigger wheels, though--even if it means a narrower tire.
> 
> Check out an article in the current edition of Car and Driver in which they test an SLP-modified GTO and Corvette. The mods added 55 horsepower to the GTO, but because SLP also switched to some snazzy-looking 18" chrome rims on Nitto tires, the car was scarcely faster than a bone-stock GTO on 17" rims.



i was wondering if you could tell me where this article is.. what month?? I have a subscription to car and driver... but have not seen this article..


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## michaelskier (Aug 29, 2005)

*Cut Fenders*



RedRacer said:


> Some can...others won't. Here's the deal... I know that I can do it. I have confidence in myself, but I don't have the confidence in a body shop that I don't know. The price of the tool ($250) is close to the amount a body shop will charge to do the work. I can sell the tool (anyone interested???) and make back most of my money.
> 
> Here's a link to the tool that I bought... http://www.eastwoodco.com/jump.jsp?itemID=6159&itemType=PRODUCT
> 
> ...



I had a body shop cut my fenders for $20 each...looks fine. A fender roll on this car may not totally do the trick. And you can't cut or roll all the way around because you run out of lip on the fender.


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## Ba Ba Black Goat (Feb 20, 2006)

*Rims*

MTI-Houston souped my 06 GTO almost too much. j/k

K&N Air Intake
Kook’s Headers w/ high flow Cats
Corsa Catback Sport Exhaust
Pedders Touring Suspension Package

Tuned and Dyno’ed at 370 rwhp, calculated out to be 450 hp at the motor. That is another 40 rwhp for a total of 50 added hp.

It’s pretty damn squirrelly. So now I need tires and wheels. I am going to purchase Michelin Pilot Sport PS2’s but I am still researching Rims. MTI suggested either Fikse FM/5’s or CCW SP500’s. 

I read somewhere else that the largest sizes that will fit are:

Front: 18 x 8.5 - 255
Rear: 19 x 9.5 - 275

But in another post here by “05Goat” he highly recommends:

Front: 18 x 8 – 245/40/18
Rear: 18 x 9 – 275/35/18

FM/5’s or SP500’s?

It would be nice to have a little bit of everything: 1) small sidewalls for handling, 2) surface area so I can take it to the strip once to see what it will do, and 3) a reasonable ride on the highway (I-10 in west La. is pretty rough!)


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## The_Goat (Mar 10, 2005)

04stangkiller said:


> The reason people want the 18's is obvious visual appeal. I was the same way. then while talkin to a local rim shop owner he described that the 17's rims are smaller in size but the amount of rubber that touches the pavment is more in turn more traction.. that is why i went with the 17's for the winter. able to have more traction and its a heck of a lot better than the nitto 555r on snow with the salt eatin my chromes.. Im polishin up the chromes and storin them in the warmth till spring.


You should stop by Fairchilds and check out the new "chrome" wheels he does for the GTO's. The guy made it sound like they won't corrode at all. 175.00 ea. :cheers


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## Tacmedic (Feb 24, 2006)

Xman said:


> Before I tried any modifications or aftermarket wheels as I was thinking in my prior post, I went and had a wheel alignment done to Pedder's recommendation. I've now have -0.3 degrees camber and a fresh set of 245s on the stock 17 inch wheels. I rotated them last weekend after 5000 miles and had absolutely no indication of strut rub. The only other aspect that has changed other than the alignment to Pedder's recommendation was the addition of SuperPro Poly strut rod bushings. I didn't need the longer studs or taller aftermarket wheels with more offset - just a proper alignment to fix the -1.3 degrees of negative camber the car came with plus the incorrect toe. Sometimes it worth trying the easy less expensive solutions first.


Best post yet. Fix the actual problem, (improper alignment) rather than treating the symptom, (tire rub):agree


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## RedRacer (Sep 12, 2004)

Tacmedic said:


> Best post yet. Fix the actual problem, (improper alignment) rather than treating the symptom, (tire rub):agree


Well, if you were in my situation with the tire rubbing on the inner fender and the outer, you know the problem isn't the alignment.


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## jcossin (Jun 12, 2009)

Has anyone tried out a 18x8 (front) and 18x10 (rear) yet? After looking through this thread, it looks like it could be done, but I'd prefer not to have to pick up a fender rolling tool and such


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## jpalamar (Jul 22, 2008)

It isn't a simple question to answer. Alot depends on the offset and if there is any suspension work.


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## jpalamar (Jul 22, 2008)

delete


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## buffgunner (Mar 23, 2010)

There seems to be some confusion here about how tires are measured. If a tire is a 245/45/17, it means the tire width is a 245 - not the tread width. You'll see many differences is tread width measurements between brands and even the same brand can be confusing.

For example, My car has 18" Sumitomo HTRZIIIs on it. Tire Rack lists tread width at 8.4" and diameter at 25.3. In comparison the 245/45/17 is 8.3" wide and 25.8" tall. As a general rule, for a given tire, in cross section, the lower the profile, the wider the tread.

BTW, the Sumitomos work fantastically and are a phenominal deal at $112 ea.


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## GM4life (Mar 18, 2007)

buffgunner said:


> *There seems to be some confusion here about how tires are measured. If a tire is a 245/45/17, it means the tire width is a 245 - not the tread width. You'll see many differences is tread width measurements between brands and even the same brand can be confusing*.


True, well put. Section width is the approx measuerment. Tire Rack list section width, tread width, rim width range and rim width.


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## firebird (Feb 6, 2011)

how wide could i go on stock suspension on 18' without any issues(including adults in the rear)? 265/255??


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## firebird (Feb 6, 2011)

i am curious how big of the offsets do i need on 285/35/18 in the rear to fit without issues on stock suspension. and how big offsetson 275.40.18

i am looking to buy new rims and would like to buy them with offsets that will be close to match without spacers.


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## svede1212 (Nov 1, 2005)

You'd like to see mid 50s to put a 285 in the back. My widened (9") 17"s have an offset of about 60.5 and with the 5mm spacers put the effective at 55.5mm. With rolled fenders, massaged inner fenders and control arm bushings it will take a squat to the bump stops and hard cornering without any rub. The wheel width should also be at least 9". Besides losing the benefit of a wider tire when you put one on too narrow a wheel it makes the tires bulge out on the sides and then they will rub on the outside.


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## firebird (Feb 6, 2011)

to get this right, so the spacers lower the offset on the rims?

so 275/285 at 9.5 wide rim you would recomend a 55mm offset. that might be harder to find, i mean selection of rims anyway. what's the biggest spacer i could use if i find smaller/bigger offset


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## svede1212 (Nov 1, 2005)

A spacer takes away offset. I think the biggest you can go is the 5mm I used. Much more and you'll be running off the hub support. I also replaced the stock studs with ARP ones. *With a 9.5" rim I would go high 40s to 50mm effective offset* either by wheel or combined with spacer. You're adding another 12.8 mm width and half that would be 6mm.


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## firebird (Feb 6, 2011)

ok so if i get a 9.5 with say 55 offset and add a 5mm spacer, the overall offset will be 50? is that right? or it will be 60mm offset


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## 87GN06GTO07IRL (Aug 10, 2009)

That would make it 50.


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## firebird (Feb 6, 2011)

ok thanks bro...that makes sense now


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## firebird (Feb 6, 2011)

" red " do you still have the rolling fender tool for sale?


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## SANDU002 (Oct 13, 2004)

With the 19's running a 275/30/19 there is no fender rub or fender roll needed?



05GOAT said:


> Here's some good reading and testing of different size tires. I am running ROH Drift R 18x8 w/ a 245/40/18 tire - 49lbs and ROH Drift R 18x9 w/ a 275/35/18 tire - 51lbs
> 
> Anyhow, I've calculated that if I go with a 245x40 18" tire up front (or 245x35 19") I get the same rolling diameter as stock. But with that I would want to mate it to a wider rear for a little extra meat. In which case, a 275x35 18" (or 275x30 19") would be the closest match, roughly 0.1" shorter than the front.
> 
> ...


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## GymChamp (Jan 10, 2010)

*All four tires wearing on inside after alignment???*

One more question on this subject please... the original 17" tires and wheels from my '06 are in storage (guess the tires might be too old to use by now, but I keep them in large plastic bags, mounted on the wheels and fully inflated, in my 68 degree basement), and I'm running an atypical setup with 245-40-18's on the front, and 275-40-18's on the rear, mounted on TSW Indy 500 wheels. Rear fenders have been rolled, and I have no scraping or rubbing problems, although I might bottom out in rear on severe dips in the road if rear seat adult passengers are on board (sorry, no children allowed!). Considering zero drop springs or drag bags to handle THAT issue. The rear tires are 26.66" high vs. 25.72" high in the front... note that 25.68" is the tire height of stock tires and wheels. My problem: ALL FOUR tires are wearing on the Inside. Alignment Camber measures are: Front Left -0.7; Front Right -0.4; Rear Left -1.2; Rear Right -1.2. A suggestion by a mechanic was to adjust cambers to more positive setting. Question is: Is that the correct/best solution? Are wheel spacers of any merit to solve this issue?? (I'm thinking spacers are for width/rubbing issues). I don't notice any negative handling issues with this unusual tire/wheel set up, but I don't race on street, strip, or track (YET?!). I just don't want to waste time & money by prematurely wearing out expensive tires! Do you have the answer??


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## magpie5 (May 23, 2015)

Newbie here. Just picked up an 06 with 19" Motegi rims. I'll probably go down to an 18 or a 17 when the time comes to get new tires. So I was wondering if anyone could tell me what the offset is for both stock 17 & 18 rims would be. Thanks.


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## svede1212 (Nov 1, 2005)

48mm on a 8" rim. Remember if you go wider you should increase the offset


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## magpie5 (May 23, 2015)

svede1212 said:


> 48mm on a 8" rim. Remember if you go wider you should increase the offset


Cool. Thanks for that. I realize that this is the revival of a fairly old thread, but has some good info. Now my interest has lead me to a couple more questions because I'm shopping for rims and comparing to stock specs. Does anyone happen to know the weights of the stock 17's & 18's? Also, how does the ride and handling compare between the two sizes with standard tire size? I get that the 17's are better for winter/all weather etc, and the 18's are better for summer tires and looking cool. But for everyday driving and fuel economy what would the difference be?

My intent here is to try to optimize a few things with a standard set of 4. I don't really want to mess with oversizing or widening and having a 2 front/2 rear configuration. Again thanks.


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## svede1212 (Nov 1, 2005)

The larger sidewall of the 17s give a smoother ride and pot hole protection (unfortunately important where I live). I don't think you'll see any significant difference in mileage but a shorter sidewall should give a little better handling on a smooth surface.


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## magpie5 (May 23, 2015)

svede1212 said:


> The larger sidewall of the 17s give a smoother ride and pot hole protection (unfortunately important where I live). I don't think you'll see any significant difference in mileage but a shorter sidewall should give a little better handling on a smooth surface.


Good to know. Some of the roads here where I live are in pretty rough shape.

BTW: I like the finish of the 17" Wheel you have on your avatar. How'd you make it like that?


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## magpie5 (May 23, 2015)

Just picked up a set of 4 ROH DriftR 18x8's so I wanted to revisit this thread now that I'm shopping for tires. According to 05Goat's post on page 1, the best fit for this is 245/40/18. Comparing to stock tire size which is 235/40/18, what is the benefit/compromise to putting a slightly wider tire?

I could also use some recommendations for a tire. I'm looking a the Bridgestone Potenza RE-11 for a good street able tire for summer all year Hawaii driving. Open to suggestions.


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## Xman (Oct 31, 2004)

Its been awhile since I worked all these issues. The 245 series tires have strut-rub issues which I think can be worse on the 18-inch rims. My findings were the soft-riding bushings in the front end allowed the suspension to flex when corning causing the tire to make contact with the strut and induce abnormal tire wear. I found synthetic strut control rod and strut top bushings with the correct wheel alignment corrected this problem and my strut rub and inside tire wear issues vanished. The Goat handled and braked noticeably better as a bonus!


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## magpie5 (May 23, 2015)

Well yes, I'm planning on replacing suspension parts as well soon. So the strut rub shouldn't be an issue. But sounds like just going with stock tire size is the safest setup. Is there any benefit to going with a 245 aside from looks?


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## Xman (Oct 31, 2004)

magpie5 said:


> sounds like just going with stock tire size is the safest setup. Is there any benefit to going with a 245 aside from looks?


Safety? The larger contact spot of the 245s should benefit cornering and braking. I've always had 245s so others will have to comment.


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## HP11 (Apr 11, 2009)

I think he means 'safest' as in least chance of rubbing etc.


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## magpie5 (May 23, 2015)

HP11 said:


> I think he means 'safest' as in least chance of rubbing etc.


Correct.


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## svede1212 (Nov 1, 2005)

The strut rub depends on tire width and sidewall height, wheel offset and camber settings. As has been covered before bushings don't play a part of strut>tire distance. 245 should fit fine in the back provided the offset is good but the front will probably have better handling with a more negative camber not possible with a wider tire.


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## magpie5 (May 23, 2015)

svede1212 said:


> The strut rub depends on tire width and sidewall height, wheel offset and camber settings. As has been covered before bushings don't play a part of strut>tire distance. 245 should fit fine in the back provided the offset is good but the front will probably have better handling with a more negative camber not possible with a wider tire.


Exactly what I needed to know. I'll be getting stock tire size for my 18's. Thanks Svede!


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## magpie5 (May 23, 2015)

svede1212 said:


> The strut rub depends on tire width and sidewall height, wheel offset and camber settings. As has been covered before bushings don't play a part of strut>tire distance. 245 should fit fine in the back provided the offset is good but the front will probably have better handling with a more negative camber not possible with a wider tire.


I've been searching around this subject a little more since I'm getting ready to upgrade my suspension, and I have acquired a set of ROH DriftR 18x8's to replace the 19x8's that came with the car from the previous owner. It seems that most forum information suggests that the 245/40/18's are an upgrade from the stock size of 235/40/18, and that a set of 245's at all four corners would not pose any problems. But this comment suggests that the 245 would actually be a downgrade for the front for alignment/handling reasons. I would like to confirm this before I spend any money on tires. My apology for the pesty persistence.


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## svede1212 (Nov 1, 2005)

magpie5 said:


> I've been searching around this subject a little more since I'm getting ready to upgrade my suspension, and I have acquired a set of ROH DriftR 18x8's to replace the 19x8's that came with the car from the previous owner. It seems that most forum information suggests that the 245/40/18's are an upgrade from the stock size of 235/40/18, and that a set of 245's at all four corners would not pose any problems. But this comment suggests that the 245 would actually be a downgrade for the front for alignment/handling reasons. I would like to confirm this before I spend any money on tires. My apology for the pesty persistence.


There are ways around it if rub is a problem. Coilovers give more clearance as well as wheel spacers. I run 255/17 on the front of mine with -1* camber using 5mm spacers and upgraded ARP wheel studs.


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## magpie5 (May 23, 2015)

Tire size calculator shows that the stock size 245/45/17, compared to a 245/40/18, are identical in diameter, and width. Circumference is 1/10 inch different between the two, larger for the 18. and total revolutions per mile are within 1 turn. (785.7 vs 784.6) The only significant difference in size between the two is sidewall as would be expected.

It would seem that the 17 would pose more of a probability of having strut rub during cornering than the 18. This with the assumption that the comparison is using stock alignment settings, and stock rim width and offset. Am I missing something?


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## magpie5 (May 23, 2015)

svede1212 said:


> There are ways around it if rub is a problem. Coilovers give more clearance as well as wheel spacers. I run 255/17 on the front of mine with -1* camber using 5mm spacers and upgraded ARP wheel studs.


I just measured the backspace on these 18x8 ROH DriftR's. Measures 6 1/8 inches. I ran this through an offset calculator to find that the offset equals 41mm. Would that be enough to clear the struts and still have an appropriate negative camber setting with a 245/40/18?


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