Does anyone know if a 18 x 7.5 will fit a rx8 with a tire size of 245/40 /18?
Thanks in advance. :dunno:

7.5 is too narrow for 245/40. 8.5 would be better.
Also you didn't mention the offset.

They will fit. I think it is recommended to have at least an 8.5" rim with the 245/40-18's.
Just the rim size is a little narrow now a 225/40-18 is more suited for a 7.5" rim.

While the tire may be wide for the wheel.

I use it for autocross and HDPE.

If you are using it for street only you will be fine.

but arent some ppl using 245/ 40 / 18 on stock rims and they are a 18 x 8..... or am i wrong? As far as offset, dont have the numbers right now.

but arent some ppl using 245/ 40 / 18 on stock rims and they are a 18 x 8..... or am i wrong? As far as offset, dont have the numbers right now.

Yes they are. The downside is slow steering response.

Does anyone know if a 18 x 7.5 will fit a rx8 with a tire size of 245/40 /18?
Thanks in advance. :dunno:

depends on the tire..

i have 245 40 18s stuck on my 18 x 7.5.

works fine.. and it is you cant curb the wheel now..

beers :beer: