How do you make 315s work w/ 18" AFR rims?

[Voice of Reason]

How do you make 315s work w/ 18" AFS rims?

I have 295 Kumho tires on my 18" AFS rims right now and they are almost completely bald after 8,000 miles. At first they weren't bad but as time went on they got easier and easier to spin, so they started to wear very rapidly. I'd like to try a good set of Michelin Pilot Sport 315s to see if they hold up any better. Right now if the car is jacked up the IRS bolt just touches the tire, so I know I will need to do something to make the wider tires fit but I'm not sure what. Is there anyone out there that has put this combo on their car? I'm thinking I will need to shave the bolt off a bit and use something like a 1/2" spacer. I want to use as small a spacer as possible so the car doesn't look ghetto but I don't want the bolt to tear into the tire either. Any suggestions?

On edit: I can't believe I misspelled AFS in the title and it won't let me change it! I'm a :loser: :-D

 

[Top_Fuel]

People have reported that they were able to run 315-30-18s on 18 x10.5” AFS wheels…without needing spacers and without any IRS bolt head interference. But as I've said before...no two Cobras seem to have the same clearances for some reason. It sure sounds like you're going to need to do something about your bolt head clearance if you go to 315s.

To solve the bolt head problem, just grind off about 1/2 of the bolt head. It's a full 1/2" tall. You can remove 1/4" of the bolt head's height and still have 1/4" left (enough meat to grab onto). I bought an extra set of IRS bolts and cut the heads down using a lathe. They look like factory bolts after I painted them. Anyway, that should solve the bolt head interference problem for you.

With 18s, you shouldn't have an issue with 315s rubbing the IRS frame. But if you do, a pair of 1/4 spacers should fix the problem.

-Greg

 

[Voice of Reason]

Thanks for the input. I would love to not have to put spacers on if at all possible. My biggest fear though is to take the rims and itres somewhere to get mounted and then bring them back to put on the car and for it to be hitting something, at which point I would be without my only car until I could get spacers. I'll have to do a lot of measuring to see what will work best. Thanks.

 

[Top_Fuel]

Talk to your local Discount Tire. They mounted a 315 on a 10.5" wheel so I could test-fit it beore buying a new set of tires. As long as I didn't drive on the tire, they wouldn't charge me for it. It's so difficult to measure sidewall to IRS clearances, you're best bet is to try to test-fit a specific wheel/tire combo. In my case (I have 17" wheels), one-eighth of an inch was the difference between a tire working or not.

One more thing... You may want to test fit the wheel/tire on both sides of the car. Some of us have less clearance on the driver's side for whatever reason. In my case, a tire that had plenty of clearance on the passenger side would barely fit on the driver's side.

-Greg

 

[venomous99]

the 18" wheels were too close w/out a spacer. either a 1/4 or 1/8" spacer will do the trick. id opt for the 1/8" to at least get the few threads of engagement more than the 1/4". again, as stated earlier, it really depends on your car.
in my case, it didnt work w/out spacers.

 

[Brad]

I'm on H&R super sport springs and I've got the AFS 18x10.5" wheels wrapped in BFG 315 rubber. They fit fine.:thumbsup: