bleucamaro

I have an oportunity to buy some discounted auto-X rubber in 225/50-16 for the fronts, and 255/50-16 for the rear. Are there any rub issues on the 255's? This is for an '89 S2 btw.

tifosiman

No way. The rears are way too tall, and too big, for autox tires. Those rears will make you car look like a dragster and perform about as well on the autox course.

Matt H

It will also "push" like a freighttrain.
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Serge944

Yes, that size will not work by any means. Besides, the largest you should go on an 8" wheel is a 245 45 16.

MTM

Those 225's are the correct size for the rears though!

Techno Duck

What is the correct size for the front tires on the D-90's? 205/55/16? I was thinking of getting 215's in the front for my next set.

M758

Why they will probably fit the 225/50's are too taller than the fronts and will jack up the cars handling. The correct rear tire size is 245/45 R16. The 255 is not too wide, but the 50 aspect is too tall.


Remeber the stock S2 and 951 size was 205/55 and 225/50 on 16x7, & 16x8.

Turbo S came with 225/50 and 245/45 on 16x7 and 16x9

M030 S2 may have had the above size.

bleucamaro

I guess I wasn't clear enough. Is there a rub issue?

As far as handling, it raises some more questions.
the D-90's I have currently have a completly shot set of 225/50's in front and 245/45's in the rear. Why would I go to a 225 for the rear?

I'm trying to shed unsprung weight, (going from my 18's 225/40-18 @ 47lbs ea. in Front , and 275/35-18 at 53lbs. ea in Rear). The 255/50 will make the rear sit about .25" higher than it is now, while the 245 will be about .4" lower. The 255 will be about 0.6" higher than the 225's in the front. Is this amount of weight jacking negligable, or will it truely affect my handling.

To Matt H, Serge, and Joe P, can you please qualify or quantify your responses? I've always been a fan of keeping as much rubber on the ground as possible. Why will this hurt me?

Serge944

A 255/50/16 has a diamteter of 25.9" A 225/50/16 has a diameter of 24.9"

Thats a whole inch and is pretty significant as it will make your gears taller. 245 is the max for an 8 inch wheel in general. The amount of sidewall bulge will make it handles and grip worse (laterally) without a doubt.

This varies from tire to tire, but for an a032r, the tread width difference between a 245 and a 255 is .1" - which is NOTHING. The section width is .7" larger though - thats where the detriment to handling comes in.

I've talked to a few 911 racers and they say that with the correct tire pressures, going a little smaller than the max in tire size will actually increase GRIP, not just handling. I can't really validate that though.

Matt H

Aside from the fact that the tire is too wide from the wheel which could cause it to "rapidly deflate" you are not putting as much rubber on the road as you think. When the tire is too big for the wheel the contact patch of said tire is reduced. Further, the car is set up to understeer from the factory and even more staggered setup with add more understeer (and with that set up a LOT more). For best results on a 944/951 I have found that 8" all around with 245/45R16 works well and the stock setup on the stock wheels is the next best. Then again, WTF do I know?
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Matt H

Lastly, with the rear tires being over an inch taller than stock you will kill the gearing.
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Spider

I've got D-90's from a 928 GT (8" Fr., 9" Rr.) Running 225/45ZR 16" & 245/45ZR 16" Kumho Ecsta Supras. Pretty nuetral w/ lots of grip.

bleucamaro

I'm not following you. This: seems to contradict this: How does adding a larger tire change the stagger? And won't I gain contact area from a taller tire?

Yes, Gearing would kill me I didn't bring it up because It wasn't a question for me. However, the rub issue still is.

Matt H

For the love of God this is not that difficult, maybe we are having a problem with terminology. The 225 front is 30mm less wide than the 255. The larger the stagger (front to rear width in this case) the worse the understeer will get on this car. For example using a 225/40R18 and a 285/30R18 will make the car understeer a ton anywhere near the limit. In an ideal world 8s all around with 225s is a nice daily setup and if you want more grip a set of 4 9" CS wheels with 245/45R16 is a great setup.

How would you gain contact patch from height? You gain contact patch from width. However, the ideal setup for a tire is a flat patch. When you "squeeze" a tire on a wheel the contact patch is not wider (it actually bows the tire and looks like a semi horizon). For example a 245/45R16 on an 8" wheel does not have as much contact as a 245/45R16 on a 9" wheel even though the tire is the same width.

It should not rub but it is not the right setup for the car and I seriously doubt you will like it.
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bleucamaro

I had always thought of stagger to mean a wider rear wheel base than the front, and the only way I saw to gain stagger was through wheel offsets; ie. a car with 3 inches of stagger will have the outside of its rear wheels 3 inches more away from the center of the car than the front wheels.

As for contact patch, its rectangular, not linear. The taller the tire is, the more rubber will be on the ground.

As far as balooning the tires, I don't see it happening. I ran a set of 255/50-15's on 15x8's with even treadwear. Also, clicking on 'specs' in this link for each tire shows the wheel size it will run on. The A032's will fit 6.5" - 10", the R3S04's will fit 8-10", and the G-Forces shown will fit 7-9. I don't think it will baloon that badly.

What I do think will happen is the car will feel more gutless than it does now, and have some rub issues.