Tire width recommendation
 

Ok so saw a few threads on this subject but couldn't narrow my decision and was wondering if I could get input on people running these setups. So I was wondering what width I should run on the front and rear on 18in rim. I was thinking 18x10 or 18x9.5 rear and 18x9.5 or 18x9 in the front. I was told wider is better to a certain point. I like to add I do track my car and more towards street performance. Also I was wondering if 38mm inset and 40mm inset would stick out or won't.(I plan on buying enkei pf07). Also I'm on stock suspension and lastly if 265-285x35x18 tires would do. Thanks for any input.

I would work out your suspension first. If not coilovers at least springs. The car is going to look stupid otherwise with wheels that size. I run 18x9.5 RPF1's all around with 265-35-18 tires and Tein S-tech springs (see attached pics for "flushness"). The wheels are +45, but you could be more aggressive to about +35 with no real trouble, but you wont know this until you have the suspension sorted, which I would take care of first :)

There is a sticky thread "will it fit" that answers your questions...

I don't think you need more than 255s. I run 17x10 +50 Rota RT5-R2 with 255/40/17 autocross tires and the grip is great. Streetability is very good as well; they ride nicely. Wider isn't always better.

I would also not run a staggered setup. the square setup allows for tire rotations and makes the car more fun and better balanced on track (unless a neutral car would be an issue for you).

Go square unless you have a good reason not to. If you go staggered you won't be able to rotate front-back. It's an even bigger problem if you end up with directional tires (very common with performance tires) because then you can't shouldn't rotate side-to-side, either.

Also, a staggered setup on the track doesn't get you anything but understeer at stock power levels. Simplify your setup by going square.

The difference between 38 and 40mm is literally exactly 2mm (or 0.08"). Nobody is going to be able to tell the difference between the two without taking detailed measurements.

Definitely go square.

I run 255/40/17 on Enkei RPF1 17x9.5 rims on the track. Going wider than that increases rolling resistance beyond what you want for a low power car. More grip also requires bigger brakes, stiffer bushings, more bracing, etc. for it to be useful. And, all of that takes the fun out of what is supposed to be a light and nimble chassis.

The above size is 0.2" smaller in final diameter than OEM, which gives me a little more torque, although my speedometer is fast by 2mph.

^I run the exact setup as above.
Run a square setup with a 255 tire and get a good Alignment