oorx7

iTrader: (2)

Just was wondering if any one has put a 285/30/18 on a 18 by 9.5 +40 rim?

After looking at many tires and there recomendations, this is not possible.

The diameter of this tire is very close to the stock size of 225/50/16. It is actually a hair smaller.

I am also planing to run a 245/35/18 on a 18 by 8.5 +38 rim in the front.

Just a couple of key specs on my car, GAB super R's with ground control conversion, stock brakes, rolled fenders (not widened), and lastly it is an FD.

The standered size I have seen is 235/40/18 and 265/35/18, the current set up I have is 235/45/17 on 17 by 8 +40 and 265/40/17 on 17 by 9 +40. I would like to make an improvment on the contact patch since I am buying tires.

I have done some searches and will keep searching, but was just seeing if some one whanted to give me some good advise.

I have put a 265/45/16 autocross slick on the stock FD rim only for drag racing purposes, and it worked fine for what I used it for. But never used them for autocross. (granted this is also not a recomended combination either)

Anyways thanks for the advice.

rynberg

I seem to remember only one manufacturer stating that a 9.5" wheel was OK for a 285/30 18. It's not recommended. If you want to run a wide tire, you need a wheel with the proper width and offset, that's just the way it is. Both of your offsets are on the very low side. I would strongly recommend considering other wider wheels for your needs.

Rx7pimpin

I was running a 275/35/18 with a 38mm offset with no problems on a 18x9.5 rim. You should be ok. 18x10 would be ideal with that set up. hope that helps

rynberg

Just because it's possible doesn't mean it's a good idea. Running big heavy wheels at a low offset puts a lot of stress on the wheel bearings and changes the suspension geometry. It's better to get wheels with a closer to factory offset, period.

In any case, a 285 is not a 275 tire. I doubt you have more than a few mm of clearance and a 285 will be 5mm wider (theoretically) on each side of the wheel centerline.

oorx7

iTrader: (2)

I think continental said the smallest rim could be 9.5"

Do you mean that the offset will be to close to the fender or shock?

Well I already have the rims in that offset and size. So I am stuck with the sizes. I don't yhink it will matter what rim it is, but they are ENKEI NTO3-M.

Now I have been doing some research and have been thinking of a couple of size combos

245/35/18 in front and 265/35/18 in rear. This I feal will bring back a more nuetral fealing.

245/40/18 in front and 275/35/18 in the rear. The only thing I don't like about this combo, is hight will be almost a 1" overall taller.

You have made me relize that I shouldn't run 285, thanks
Can you recomend a tire combo that you think would be best.

Thanks rynberg

rynberg

Well, I'm running 235/40 and 265/35 on the same size wheels as you're running. This setup does understeer a little bit in the hairpins but is much more reassuring for medium to faster corners. Those tire sizes are ideal for those rim widths. However, a 245/35 should work quite well, so 245/35 and 265/35 is probably your best bet for minimizing understeer, especially since you can control the height of the car.

I like the 235/40 up front for two reasons:

1. They match the diameter of the 265/35s in the rear. I can't control ride height so I want to avoid jacking up the rear more than it already is.
2. The 235/40 makes the car sit almost 1/4" higher than with a 245/35, giving you a hair more clearance in normal street driving. Believe me, that 1/4" makes more of a difference than you might think when it comes to clearing my steep driveway.

Rx7pimpin

Rynberg although I understand your point. The questions was not if is a good idea or will it change suspension geometry. It was will it work? and it will work!

Nor did I say that a 285 and 275 are the same tire!

rynberg

You clearly told him that you were running a 275 on a 9.5 +38, so it should work (him wanting to run the 285 on a 9.5 +40). And I'm saying that it most likely will NOT work. You can ask any of the Gram Lights guys -- they've got 18x10 +38 with 285/30s and had to roll the fenders. A 285/30 will be slightly narrower on a 9.5" rim and the offset is 2mm farther inboard but I bet it would still come EXTREMELY close to hitting the fender, if not outright hitting it. It would probably come down to the exact camber setting and individual tire manufacturer.

I don't know about you but I don't feel comfortable making a recommendation with zero safety margin (or worse, less than zero safety margin).