Hello guys! i haven't been on in forever!

Just wondering if 245/40/18 tires are ok to put on stock rims with out having to do any modifications to the car? it's not lowered or anything suspension wise.

Edit: it's 2004 GT 6spd MT, I have 245's on the back now i want to have the same tires all the way around so the question is more regarding the front fenders etc.

Thanks!

 

yes, no issues whatsoever

 

Awesome Thanks man!

 

I'm currently running 245/40/18, but I'd suggest that 225/45/18 may be the better way to go.

In the December 2013 issue of GRM, page 126 there are lap time results for different tires on a road course.

Average/Best Laps
BFG Rival 8" rim - 205/50/15 - 84.03/83.65
BFG Rival 8" rim - 225/45/15 - 83.93/83.65
BFG Rival 9" rim - 225/45/15 - 83.47/83.18

Note that the 205 and 225 on the 8" rim have essentially the same performance. Going to a wider rim was needed to allow the 225 to improve upon the 205 results. This implies to me that you don't want to put the widest tire possible on a given rim width (eg. 245/40/18 on a 8" rim). You're better with the tire to rim ratio being a bit lower. 225/45/18 might be faster on the OEM RX-8 rim, not to mention a bit cheaper and more fuel efficient.