Most of the tire makers I have seen specs for say 8.5" wheels are only good for up to a 255 tire. Yes a 275 will fit but it won't hold the same load or be as safe. If you have an issue they won't warranty.

Also, I just called my friend who has been a manager at discount tire for years and he said they would not do it and if you didn't get it in writing that they said it was ok you may be SOL.

 

Well, I guess I wouldn't do what your trying to do. It all concerns tire height. The car's handling bias and VDC are expecting to see about a 1" difference in overall diameter from front to back. Stock's are 225/45/18 = 25.8", 245/45/18 = 26.7". 245/40/18 = 25.7", 275/40/18 = 26.7". So that would be best with your 245/40 front. 285/35/18 is 26.0" = too low. 285/40/18 is 27.0" = too high. However 255/40/18 is 26.1", 285/40/18 is 27.0" = OK.

So, I guess what I'm saying is go with 245/40/18 up front - use 275/40/18 in back. Go with 255/40/18 up front - use 285/40/18 in back.

BTW, I'm running Dunlop SportMaxx 245/40/18 and 275/40/18 on Nismo 8.5"/9.5". I was running Dunlop SP9000s, and the SportMaxx rears are wider than the SP9000s. The fronts are about the same. With an STB, the car handles like its on rails.

Lou

 

yea i got all the strut bars, and tie bars, front and back so i hope it will take turns better now....thanks tho , i'll get the 275/40

i def dont want to mess up my vdc

 

can u post pics of ur car?? or pm them to me?

 

ok one little problem i ran into, the tires i was gonna put on the front are 245/45/18 which is 26.7" high and 275/40/18 in the rear are 26.6 which is lower but 285/40/18 are 26.9" high and .2 inch which is within 1" for the vdc....will this be ok??? or should both Sidewall sides(middle number)be the same front and back ?

i see that on a lot of wheels or on most websites they always mix them like 245/35/19 front and then 275/30/19 for rear ???

will this really mess up my vdc and make it come on , esp around hard cornering or autocross?????

should i just try to sell the tires i got now and start over???

 

i also see this 245 40 18 (front) and 285/35/18 (rear) which is 25.7" front and 25.9" high in the rear

 

I dont know hoe safe that is, but, I can guarantee you that those tires run bigger and wider then any other tire. They have a bigger sidewall. Whe I baught my 20 I ordered those KDW2 in 255 and 285 and iForged told me that they would fit but I would have rubbing since they are bigger then most other tires. So in reality its as if you are running a 285 in the rear of say a toyo tire. Thats not safe and smart at all. But it does look nice. And btw, someone mentioned nice snow tires. These are strictly summer tires.

 

I like to think of them as a drag radial's brother.

 

UPDATE:
Have been to 3 autocrosses since new and they have stuck through everything. Cant get them to slip at the track, wont budge road coursing unless i REALLY push it, and no tires take the abuse mine have and live to tell the tale. I LOVE these tires.

Measured 12/32, 13/32 new, have over 3500 miles on them, ~8 passes at the track and 15 autocross runs. Pretty damn good for an extreme sport summer tire! 3000 miles??? you bet i can!

They also saved my life this last weekend. I had a truck drop a hay baiul about 100 yards in front of me in pouring rain. As it was at night, didnt see it until it was about 100 feet in front of me... i avoided it on the shoulder, these tires handled in the rain like they do in the sun!

Kevin

 

I have these on my OEM 18's. These tires are unique looking and do offer great performance in wet and dry conditions, but the noise from them is unexcusable. I've had better results in performance from other tires with less noise, though. I bought the car with these and they probably have another 10K+ miles left in them, but I wont buy them again.

 

Don't mean to revive an old subject here but i've been curious and may be a possibility in the near future that i'll be doing something similar to this.....

For those who are against having the 275/35's on the oem 19's, I still don't understand why having 275/35/19 on the oem 19x8.5(rear) would be any different(when it comes to safety and handling) from these aggressive width and stretch tires on this thread....https://g35driver.com/forums/picture-share/210265-aggressive-wheels-stretched-tires-post-em-up-some-nsfw.html

In my opinion, having it "stretched out" would have the same concerns as the ones that's "stretched in"....wouldn't it? School me on this because i don't see many people complain about having a super wide rim with smaller width tires which also stretches the sidewall to a considerable amount.

And for those who do have the 275/35 on the oem 19's AND who has been running them for quite awhile...any issues? problems? irregular treadwear maybe(besides the usual factory camber issue)? Thanks guys

 

bump...

*crickets* *crickets*

 

neither form of "stretch" is optimal for performance, which is why I'm against both. Both have their inherent risks.

 

I really feel like it's a case of people regurgitating what they heard from others. I would like to see one example of an accident or tire failure that was proven to be the result of tires being either under or oversized in width. The same speeches are heard on every message board. I really do not know why people present 2nd person opinions as facts.

 

So where is or "proof" that a 275 mounted on an 8.5" rim is better performing that a 245/255/265? Why do manufacturers have width specifications at all? Go ahead and just mount a 305 on an 8.5" wheel, I'm sure it will physically fit.