It is time to replace the tires on my 6 M/T coupe. For those who have switched to 245/40ZR18 front and 275/40ZR18 rear how are they doing? I am curious how the rears are on the 8" wide rim.

 

Three forums now, huh? The answer is still DON'T DO IT?

Lou

 

Yep and read all three of your answers. Problem is the question is posed to those using the setup, as opposed to those who just want to say no!

 

The problem is not many will be running 275 rears on 8" wide rims. Thats just asking for trouble. I ran 275 rears on my TE37's (when I had my 350Z) on a 18x9.5 rim. What you're looking to do is not feasible. If you want to run 275 in the rear, get new wheels.

 

themyst

This guy's not worth our time.

Lou

 

fwiw, One of the top autocross guys runs 275s on his stock 7.5/8" wide 17s, and puts the sidewalls through a lot of stress without popping the tire off the rim, so it can be done safely, you will just have a lot of bulge.

 

Lou,

Just because people disagree with you is no reason to bad mouth them. Rather then blasting people why don't you try to be positive and rather than saying don't do it or it is a liability why not share with the readers exactly what the issue is. If you check the 3 forums several are running the size I mentioned with no problem. If you could tell me and the others what the tire will do that is so dangerous that would be a big help.

Kirk

SAE Engineer

 

Kirk,

Check the tire manufacturer specs for a 275.

What is the MIN wheel size they specify for a 275 tire?

All are 275/40 18, except where noted:
Bridgestone S-02: min wheel size 9” - recommended 9.5”
Yokohama AVS Sport : min wheel size 9” – recommended 9.5”
Toyo Proxes T1-S Ultra: min wheel size 9” – recommended 9.5”
Pirelli PZero Asimmetrico: min wheel size 9” – recommended 9.5”
Continental ContiSportContact2 (275/35ZR18): min wheel size 9” – recommended 9.5”

Noticing a pattern yet?

It may be POSSIBLE to put a 275 on an 8” wheel. It is just not a good idea.

It sounds like you are just looking for someone to tell you to go ahead and do it, since you don't want any input from people that aren't running the setup. If you have been to 3 forums and asked the same question, but haven't gottent he answer you are looking for, maybe you are looking for the wrong answer.

In the end, it’s your choice, Kirk, but why would you want to run something that is SOOO far out of spec. As an SAE Engineer, you should know that running things far out of spec is not a good idea, nor the optimum solution.

Like themyst, and others I'm sure, said, if you want 275's in the rear, buy new wheels, or find someone to widen your stock wheels.

As for the autocrosser, what tire is he running? Hoosier recommends a 10” wheel for their 275/35 18 and a 9.5” wheel for their 275/40 17 DOT tires.

I find it hard to believe that a 275 tire on an 8” wheel is anywhere near a optimum setup. If he does wheel with that setup, I can't imagine what he would do with a properly sized setup.

D

 

Thanks for the info. I have rec'd several PM's from folks running the setup I mentioned. All of the info has been helpful thanks.

 

He's a national champion autocrosser and he runs hoosier 275/(40, i think) on stock front 7.5" rims and rear 8" rims. Can't go to a wider rim and stay in stock class.

 

"It sounds like you are just looking for someone to tell you to go ahead and do it, since you don't want any input from people that aren't running the setup. If you have been to 3 forums and asked the same question, but haven't gottent he answer you are looking for, maybe you are looking for the wrong answer"

Not at all my friend. Check the posts. Several running the setup I am looking at with no problems. I am not looking for any one's approval. Just interested in actual user feedback. Is that so unusual? Thanks anyway!

 

I use SSR GT-3 Front: 19" X 8.5" with 245/35/19 and Rear: 19" X 10" with 285/35/19, and I like it. They give me much better handling and heavier steering feel.

 

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