# 1/8 mile tire question



## Chris-Austria (Dec 23, 2010)

Hi!

Today I raced my GTO the first time and it was a very nice experience.
I'm totally new to this and maybe need some advice to improve my skills and my car.
The biggest problem was spinning tires in 1st gear, it was very difficult to get a good start and not to spin the tires all the time up to 2nd gear. I raced with my BF Goodrich Radial TA 235 60 15... not a good choice I guess.

What tires and what tire size would fit on my car and improve traction? Slicks, semi Slicks or modern tires like Conti Sport Contact? 
Rims are 15x7"... if they fit on these wheels I can change the tires before the race (no slicks in this case because I'm not allowed to drive them on the street). Otherwise I would also buy 2 new rims for the rear... Any suggestions?

My best 1/8 mile time today was 9.201... not sure if it's good... but I'm pretty sure I can run a high 8 or a even 9.

Thank you!
Chris


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## Chris-Austria (Dec 23, 2010)

What about these: http://www.summitracing.com/int/parts/bfg-54003/overview/
Description sounds good and should fit my rims.. are they too small? (235?)


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## ALKYGTO (Mar 29, 2010)

Not a big fan of drag radials, I prefer the bias plys....More sidewall flex for better hook and less shock to the drivetrain. What about these? http://www.summitracing.com/parts/mtt-3752/overview/ they might be a tight squeeze but with the right offset rim I think they would work. Might be more sizes available too but that is all I saw on Summits website. Give them a call if you can and they can probably help you with other sizes.

I used to run a 275-60-15 on the back of the Alkygto but they would go up it smoke at 60 mph. Great street tire but not so good for the drags.


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## Chris-Austria (Dec 23, 2010)

I know exactly nothing about drag races.. first time yesterday. 
While walking around I could see that many others use "Hoosier" tires.
If I want to use my 15x7 wheels I can use up to 255/60/15 I guess, do you think I should also buy new wheels and use larger tires? I don't have that much HP... maybe about 450.

The tires you showed me look good and the price is okay.. but I might have problems to fit them on the rear of my car.
Do you think slicks with no profile like the Hoosier could "hurt" my transmission or rear end?
What I think I need is the smallest tire that will provide good traction (better than the BF Goodrich Radial TA I own) and that will not hurt my transm. or diff.


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## ALKYGTO (Mar 29, 2010)

edit.


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## ALKYGTO (Mar 29, 2010)

Hoosier's are good too. Also a brand called Phoenix I believe. Anything with a soft compound and a flexible sidewall.

A lot of drag racing is in the technique too.

Mickey Thompson Performance Tires & Wheels

Phoenix Racing Tires

Hoosier Racing Tire - Tires Designed For Champions

I would check out these manufacturers and see who has a size that will fit your car. Most of them show what rim size their tires fit and have the section width so you can compare to what you have now. I agree that you should run as close to the same diameter as your street tires or you will possibly hurt your gear ratio. 

What kind of MPH did you run also?


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## Chris-Austria (Dec 23, 2010)

They only printed a sheet with the racers names, cars and times. I wrote them today if they can send me all details of my 4 runs. First the track was wet.. I ran 9.96. But I really thought that I should be 1 sec. better if the track is dry.. maybe with the proper tires.
My rear end is a safe-t-track HD from 69.. but I don't want to test how far I can go until it breaks.. so I'll look for some good tires in the range of 235-255mm, thanks for the advice!


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## BearGFR (Aug 25, 2008)

I'm running Nitto NT555R P275-60-15's on the back of my car, on 15X8 reproduction Rallye II wheels (from Specialty Wheel - important because they have a 4.5" backspaces whereas all the others I found had only a 4.25" back space). They hook very well, are street legal, and seem to be a decent compromise between dry and wet traction.

Bear


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## Chris-Austria (Dec 23, 2010)

What do you think of the Mickey Thomoson ET Street Radial? They offer 235/60/15 and 255/60/15.. both would fit my 15x7 rim.
All manufactures say "don't mix radial and non radial tires". That's why I won't use bias plys even if they are better.. I don't want to spend too much money for one or two drag races the year. 

Do you have experience with one of these tires?

1. Mickey Thompson ET Street Radial: http://www.summitracing.com/parts/mtt-3756r

2. BF Goodrich g-force TA Drag Radial: http://www.summitracing.com/int/parts/bfg-54003/overview/


I don't think I need that much traction like Bear.. if I use the Wallace Racing calculator my quarter mile time is 14.38 (1/8 mile is 9.2) which isn't that good. What should I expect to see with my GTO and better tires? 
How much improvement is realistic between my BF Goodrich Radial T/A and one of the tires above? I hope for something below 9 sec on the 1/8 mile.


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## Bill H (Aug 4, 2013)

I know a lot of guys that jumped on the MT ET Streets and never looked back. I can't say they made a bad choice from the results. The Nittos are another tire that I've seen people have a lot of luck with.

You mentioned it was your first time and you don't have a lot of experience and like others have said, there is a lot that goes into the mix for a successful run. Once you land on a tire don't be afraid to play around and heat them up before your runs. Some really like a good melting before hand while others will just get slimy and not hook.


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## Chris-Austria (Dec 23, 2010)

The MT ET Streets are available in 235/60 and 255/60... do you think there is a big difference (traction) because of the 20mm? And which is the better choice for a 15x7 wheel?

And yes, it was the first time. I appreciate every information you have to improve my times 
I had to drive through the water passage with my street tires and on the last (and best) run I made a little burnout after the water passage on dry ground. I could feel that the traction was a little better in 1st gear but not really good. I don't want to build a drag car.. but I hope better tires can improve my ET.


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## BearGFR (Aug 25, 2008)

For bite, the MT's are about the best there is (or so I've been told), but I've also heard their longevity and wet pavement traction are both pretty poor. I went with the Nitto's because they're supposed to be "decent" in all three areas and I don't want to have to be terrified to drive my car if I happen to get caught out in the rain.

I like my Nitto's just fine, but after being on the car for over a year and running the Power Tour (I leave them on all the time) they're getting close to needing replacement.

I have no direct experience with BFG's so I can't really comment on them.

Bear


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## ALKYGTO (Mar 29, 2010)

Chris-Austria said:


> The MT ET Streets are available in 235/60 and 255/60... do you think there is a big difference (traction) because of the 20mm? And which is the better choice for a 15x7 wheel?
> 
> And yes, it was the first time. I appreciate every information you have to improve my times
> I had to drive through the water passage with my street tires and on the last (and best) run I made a little burnout after the water passage on dry ground. I could feel that the traction was a little better in 1st gear but not really good. I don't want to build a drag car.. but I hope better tires can improve my ET.


Honestly probably not much difference between the two, I would say run the smaller size because that is closer to the size of your street tires and you won't have any clearance problems. It will fit the 15x7 rim just fine. 

Street tires are terrible at the strip typically and you for sure don't want to run them through the waterbox. They pick up water in the treads and then throw it up in the wheel well so even if you do spin it all out it still drips down on the tires. And they are like driving on ice when they hit the layer of rubber on the strip.


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## Chris-Austria (Dec 23, 2010)

I couldn't go around the water at this track 
What about longevity if I buy some Slicks or Street Radials and only mount them for 2-3 races every year? The rest of the time I would put them into storage.

235/60/15 will fit for sure, that's the same size I have now.. but I'm pretty sure that 255 ain't a problem as well. 
A friend sells his Slicks, 28x10x15 on 8.5x15 with 4" backspace... is there a chance they will fit?? And how good are Hoosier Drag Slicks? Good or bad choice if the price is good?


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## ALKYGTO (Mar 29, 2010)

See if he'll let you bolt them on to see if they fit. 

Hoosiers will be fine, how old are they? Dig your fingernail into them to see if they are still soft. Make sure they are not dry rotted. Slicks come in a couple of different compounds too btw.


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## leeklm (Mar 11, 2012)

Hey Chris, your engine is similar to mine, which is in the low 400hp range and 500lbs of tq. I ran a best of 13.7 in the qtr on my street tires. My best times were taking off easy to eliminate tire spin. Any spin at all and my eta suffered. I ran at a pro track, so the launch pad was very sticky and I could avoid the wet box. I planned on borrowing a set of slicks to try them out but season is over. If you plan on getting to the track on occasion, buy an extra set of rims to mount your slicks, and carry them to the track in the trunk.

But beware, hard launches on a sticky track and slicks will most certainly shorten the life of your 4spd and 10 bolt rear! Also, most tracks require a driveshaft safety loop when running slicks. Attached is a pic of the one I got from summit. 

Sent from AutoGuide.com Free App


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## Chris-Austria (Dec 23, 2010)

Do you know this calculator? I was told it's pretty realistic..
1/8th to 1/4 Mile Et Calculator - Wallace Racing

Your 13.7 is a 8.75 on the 1/8 mile.. that's what I want to see (okay.. I said 8.8 is my goal to a friend..)

Thats a great time you got, must be fun to drive  I'm not sure if I can get there, but I'll try! I don't want to hurt my drivetrain.. should I use Street Radials (235) instead of the Slicks? Or is the wear on my 4spd and rear end the same with both?

my safety loop:


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## leeklm (Mar 11, 2012)

The extra traction with slicks will put a lot more stress on the drivetrain than you will have with street tires, which kind of act like a "safety valve" when they spin.

My engine guy used to drag race his pontiacs quite often, and in his words "that track likes to eat 4spds".

I personally do not have enough experience at the drag strip to verify the reliability of the Muncie or stock rearend on a sticky track.


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## Chris-Austria (Dec 23, 2010)

Maybe it isn't worth the risk.. others said I can run them without big worries because my engine isn't that strong and the tires aren't that big...
My rear end is a 69 safe-t-track HD with Posi and 3.55 gears. I personally think that the 4spd may be the weaker link, but I don't know how durable they are. 
The tracks are not too sticky... about equal to normal roads (a guy there told me who didn't miss one race) It was a public show where I started... place 12 of 39 but there are also cars with 700-800hp and slicks... they didn't extract those cars from my class. Street cars are maybe 4-5 in my area that are faster, but not much and if I also run slicks I think I can beat 3-4 of them 

Here's a pic of what I tried today.. the wheels have too less backspace.. but the tires will fit on a proper wheel:


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## leeklm (Mar 11, 2012)

Regarding your question on 1/8 mile time, mine was about 9 sec. Here is one of my time slips where i turned a 13.85


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## Chris-Austria (Dec 23, 2010)

I wrote an email to the Raceday Crew if they can send me my time slip.
My 9.204 is the total time I was told, 1/8mile plus reaction time. So I really want to see the time slip now 

Something like yours would be interesting.. 60ft, reaction and mph is what I want to know. My opponent was a Mercury Cougar (3 times) and he won 2 runs pretty close, but at the end of the track I always was faster and on the 1/4 mile I had won every time I guess.. it was just the lack of traction in 1st gear that slowed me down first.
My other opponent was a Chevy Nova.. he didn't have any chance to win 

You can watch my runs.. For the stats in the Video I assumed that my mph was about 78 (125kmh) because another time slip I saw with the same time had 128kmh.. 
I'll correct it as soon as I get my time slip.


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## BearGFR (Aug 25, 2008)

Glad to see that you're having fun!

Yes, if you can get it to stick you'll definitely be spanking that Cougar 

Bear


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## Chris-Austria (Dec 23, 2010)

I like the moderator.. at every run he told the crowd how much he likes my car. 
("do I have to stay neutral as a moderator? - I must be allowed to say that the GTO on the right side is really wicked")
It's really funny, I didn't expect to be that excited about drag racing. It's not only the race.. it's the people you meet, the reaction of the crowd and the feeling to be a part of it  

I want to keep the "street car look" so I won't use Slicks... Now I'm searching for good street tires that will improve traction above the level of my BF Goodrich Radial TA.
I'd like to use the Nitto you told me but 275 is just a little bit too much for my 15x7 rims.

The Mickey Thompson ET Street Radial and the BF Goodrich g-force TA Drag Radial have 235 and 255 available which would fit. If I can find used rims (8x15) I will order the Nitto tires.

Do you think I should use 275/50 or 275/60? Maybe 275/60 will touch my wheel housings?! Is there a difference in performance?
And how much difference in ET is realistic between my BFG Radial TA (235/60) and the Nitto NT555R (275/50)?


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## BearGFR (Aug 25, 2008)

Chris-Austria said:


> Do you think I should use 275/50 or 275/60? Maybe 275/60 will touch my wheel housings?! Is there a difference in performance?
> And how much difference in ET is realistic between my BFG Radial TA (235/60) and the Nitto NT555R (275/50)?


Hi Chris,
You're over-thinking it a little. On any run, the car's either going to hook or it's not. Having a fraction of an inch wider or taller tire isn't going to affect it nearly as much as your driving technique and personal reaction time will.

It's going to take you some time to 'learn' the car and the tires. You can vary launch rpm up and down, vary your technique (dump the clutch all at once or try to "finesse" it a little) - all until you figure out what works best for you and for the car. The better tires give you more of a fighting chance to optmiize the launch, but you're still going to have to learn what works and how to be consistent in doing it. No matter how good the tires are, any car can still be a dog with poor technique.

Manual cars subject the drive train to more shock than automatics do, so if there's a weak link anywhere you'll probably find it  

That's ok - the main thing is to get out there and have fun.

Bear


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## Chris-Austria (Dec 23, 2010)

You're right Bear! And I think I will have a lot of fun 
So it will be the 275/50/15 if I find a wheel or something like the other 2 (255/60/15).
Hope not to discover some weak links in the near future since the car now runs really nice and well. To avoid it as good as possible I think not using the Hoosier Drag Slicks is a good idea.
Thanks!


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## BearGFR (Aug 25, 2008)

If you want to be sure, I'd recommend using a tool like this:

http://www.summitracing.com/parts/php-01201

To make sure your wheel/tire combination will fit and not rub. I used one of those when selecting mine, and found that 275/60-15 would fit but 275/50's might not. You can get tire dimensions (the most critical for this purpose being the overall diameter and the section width (maximum width) ) - usually from the tire manufacturers web site and/or from a large tire supplier site (like tirerack.com)

Bear


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## Bill H (Aug 4, 2013)

Chris, like Bear said...don't overthink it. You'll see a lot more gains from getting some track time under your belt and getting familiar with your setup.

Just remember little gains on the short end equal big gains at the top of the track. Shaving time off your 60' will translate to some nice gains overall. 

Your reaction time isn't going to do anything to lower your E/T, but it may put you in front of the car next to you.


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## leeklm (Mar 11, 2012)

:agree

Yep, my times have ranged from 13.7 to 15.xx, all on the same 255/60/15 tire! and that is not factoring in my reaction time.

By the way, your track is set in a much more scenic backdrop than mine!!


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## Chris-Austria (Dec 23, 2010)

I'll have to replace my clutch linkage, it's now working but it's not really good. I agree that I need more track time.. but I don't often get the chance to run on a racetrack.

What I will do now is repair the clutch linkage, get some better tires for the rear and get some practice with that. 

The tool you showed me looks good.. if I find a used wheel I will put on a tire and test it directly or I'll ask if someone has such a tool here and can borrow it to me 

I'll also have to practice how to make a burnout with my 4spd to warm up the tire.

Without hoping to get a better ET I'll change to roller rockers anyway.. but maybe they can also help a little. I got the feeling that my engine likes to be reved up to 6000rpm in 1st gear, but in 2nd gear it was better to switch the gear at 5600rpm. Is this possible? I think I could feel the engine to be out of power at 6000rpm in 2nd.. maybe the fuel delivery isn't as good as it should be there or the carb is too small (750cfm with 1" tapered spacer). Switching gears a little earlier and making a little burnout on dry ground changed my ET from 9.6 to 9.2.


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## leeklm (Mar 11, 2012)

Chris, similar to my motor, yours is probably not gaining much power beyond 5K rpm, although it feels like it is screaming on the track. I would try to shift at 5,500 every time just to be consistent.


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## Chris-Austria (Dec 23, 2010)

I guess you are right, I'll try it next time! (even from 1st into 2nd gear).


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## Chris-Austria (Dec 23, 2010)

Bear... all your advices always worked well for me...

take a look


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## BearGFR (Aug 25, 2008)

Awesome - let us all know how you like them!

Bear


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## Chris-Austria (Dec 23, 2010)

Maybe I'll get some used alloys (15x8) soon and then I can mount the tires.
Would you say 15x7 is too small for these tires or could I try them with my 15x7's?


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## BearGFR (Aug 25, 2008)

I would use the recommended rim width. If the rim is too narrow it changes the tire contact patch, and also puts funny forces on the side wall.

Bear


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## Chris-Austria (Dec 23, 2010)

7.5 to 9.5 is recommended.. so I'll have to wait for some 15x8 rims

funny forces are not what I want on the racetrack or on the street... even if my rims are "only" 0.5" too small


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## leeklm (Mar 11, 2012)

those should work much better for you at the track. I have a set of GoodYear Eagle GT II on mine, which are pretty similar I think to your BF GoodRich tires.


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## Chris-Austria (Dec 23, 2010)

Another question..

What backspace would fit best if I use 15x8 wheels? Is 4.5" enough with the 275/50/15 or should I look for wheels with 5" or even 5.5"? To buy the tool Bear told me is pretty expensive, maybe someone can tell me what he has on his GTO on the rear.

The 15x7 with 4.25" backspace fit well.. (235/60/15) but it looks like there is a lot of space on the inner side and just a little on the outer side.


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## ALKYGTO (Mar 29, 2010)

Chris-Austria said:


> Another question..
> 
> What backspace would fit best if I use 15x8 wheels? Is 4.5" enough with the 275/50/15 or should I look for wheels with 5" or even 5.5"? To buy the tool Bear told me is pretty expensive, maybe someone can tell me what he has on his GTO on the rear.
> 
> The 15x7 with 4.25" backspace fit well.. (235/60/15) but it looks like there is a lot of space on the inner side and just a little on the outer side.


Put the 15x7 rim and tire back on and measure the clearance to the inside. If you have 3 inches of clearance and want to run an 8" rim then add an inch to the backspace i.e.. 5.25" and you'll still have 2" of clearance.

I run a 15X10 rim with 6" backspace on my car but it is a different year obviously.


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## Chris-Austria (Dec 23, 2010)

I will test it. Maybe I'll put on the 275/50/15 on the 15x7 just to see how much space is left and if I only change to 15x8 it will be obvious which backspace should work I guess.

Can someone tell from experience which backspace works best if you use a 15x8 wheel and a big tire like a 275mm on the rear?


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## BearGFR (Aug 25, 2008)

Chris-Austria said:


> I will test it. Maybe I'll put on the 275/50/15 on the 15x7 just to see how much space is left and if I only change to 15x8 it will be obvious which backspace should work I guess.
> 
> Can someone tell from experience which backspace works best if you use a 15x8 wheel and a big tire like a 275mm on the rear?


You can figure it out without the tool. Remove the rear tires, lay a straight edge vertically across the face of the brake drums to measure where that surface lies in relation to the center of the widest part of the wheel well. (Do both side in case the axle isn't perfectly centered). From that you'll be able to determine where you want the centerline of the tire to be in relation to the brake drum face. That's the offset and will be positive if the tire centerline needs to be closer to the frame than the brake drum face, negative if it needs to be farther away. "Add" the offset value (mind the sign) to half the rim width and you've got the backspace you need to put the tire where you want it.

Bear


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## Chris-Austria (Dec 23, 2010)

I looked at my rear wheels and this is what I saw:

- the shocks look like they are the closest part to the tire
- the wheel well is about 2" away from my wheel (7x15 bs 4.25 with 235/60/15)
- I have about 0.5" space on the outer side 

What do you think, is it a good idea to put the 275/50/15 on my rim, mount it on the car and look how much space is left inside and outside?
The 275 tire will have the same width on the 8x15 I guess, so I should be able to see how much more BS is needed. The only thing I will have to consider is that a BS 4.25 on a 7" wheel is equal to a BS 4.75 on a 8" wheel. So if I still have some space left I can use the 4.5 BS wheels I found, otherwise I'll have to order them with 5.5 BS and check if there is enough space on the inside of the wheel well. (there are only these 2 sizes available)
Please correct me if I'm wrong, but the 8" instead of the 7" wheel will not make any difference regarding space in the wheel well?! Only BS and the new tire are the 2 important things I have to measure?!

I'll also follow your instructions Bear.. just want to be sure to order the correct size since I pay more for shipping than the wheels cost.


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## BearGFR (Aug 25, 2008)

Rim width will have a small effect on the overall width of the tire. The widest part isn't at the tread, it's about halfway between the bead and the tread where the sidewalls bulge out a little. Pulling the bead in a little (due to the narrower rim) will also pull the sidewalls in just a little. It won't be a huge difference, but it will be a difference. 

But to answer your question, no it wouldn't hurt anything to go ahead and mount the tires on the wheels you have just to get a visual on where you're at with it now.

Bear


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## Chris-Austria (Dec 23, 2010)

This is the 275/50/15 on 7x15 BS 4.25:










I think it may scratch on the outer side if the rear goes down a lot (like with 3 passengers in the rear). But I drove it and it works great. I'll not carry someone with me when I go to the racetrack so maybe I should stay with this size?!

If I now order 8x15 wheels and get them with a BS of 4.75 the distance on the outer side will be the same as with my 7x15 and BS 4.25? 
Maybe I'll try to get some 8x15 with BS 5 to have some more space on the outer side.. the inner side has still plenty of room (about 1.75")

With a BS of 5.5 and a 8x15 I'm sure I could fit a 295mm tire without any problem.. but 275mm is big enough for my purpose!


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## Chris-Austria (Dec 23, 2010)

Next question..
Which wheel would you use if you were me? I can't decide which one would create a proper look... First I thought that chrome is the way to go because I'll keep the Cragar SS front wheels on the car. 
I want to use 8x15 with 5" BS (or 4.75" if there is a nice wheel available).
Any suggestions??

This is one of my favorits, but don't know if it will look good:
http://www.summitracing.com/int/parts/crw-27580547500/overview/

This one may also look good:
http://www.summitracing.com/int/parts/usw-37-5834p/overview/

But as I said.. I cant really imagine what is a proper wheels for the racing tires... I'd appreciate every suggestion or if you show me what you use for the track.


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## BearGFR (Aug 25, 2008)

On a race car, folks usually go for whatever's the lightest weight. For what you're wanting to do though it's really not going to make a huge difference. I'd go with whatever you like the looks of the best, and you think would be visually pleasing when combined with your front wheels ---- just in case you feel the urge to go out "hunting" some night 

Bear


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## Chris-Austria (Dec 23, 2010)

The Bart Wheels and the Circle Racing Wheels are both steel but weight only about 19lbs. My Cragar alloys are about 23lbs and the standard steel rims are about 25lbs. So I agree, the difference in weight won't be a very important thing for me.

I can't find a wheel that looks like the Cragar SS.. there is one from the Summit brand that is alloy but it has a BS of 5.5". I'm sure it would fit, but don't you think the wheels belong as much on the outer side as possible? I have some 6mm spacers at home, but I will need some other lug nuts or studs to mount the wheels, right? Is it very hard to change the studs or could I use just some other nuts? (I don't know what they are called, but the Centerline's I tested had some special lug nuts to extend the studs... can't express this better in english, sorry


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## ALKYGTO (Mar 29, 2010)

Most tracks over here require longer wheel studs with slicks Chris. You would have to pull the axles and have new studs pressed in. Check with your local track to see if this is required.

And I would recommend a drive shaft safety loop also if you do not have one. You don't want to pole vault down the track. :cheers


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## Chris-Austria (Dec 23, 2010)

I don't use Slicks, I already have the Nitto 555R tires and want to use them on a "standard" rim. (8x15, bs between 4.75 and 5.5)
There is no need for longer wheel studs if the lug nuts can be tightened I think 7-8 turns. If it's possible with the Cragar SS than it is possible with these rims I showed before.

But if I go with the 5.5" BS I'll have to use the spacers and this will probably get me into the trouble of 7-8 turns with the lug nuts. I saw some special lug nuts that have a longer thread and can adjust for lets say the 6mm spacers.. don't know how they are called.

At the track there isn't a requirement for longer studs or a safety loop. To pull the axles sounds like a lot of work.. or is it easier than I think?

I already have a safety loop:


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