15x7 v.s. 15x8

Is there a fitting difference when it comes down to the two sizes?
I have 98 ZJ rims (15x7) and currently have 31x10.50x15 tires. Looking to replace them and found Trxus STS but only comes in 31x11.50x15. Anyone know whether it's doable or would cause problems?

anyone?

According to this http://www.intercotire.com/site35.php that tire should be run on a 15x8 to a 15x10. I know you "can" run 11.5" tires on a 15x7 wheel but it is not recommended.

not exactly the same, but I just got 33 - 12.5 15s put on my 15x8 rims. manufacturer recommended 8.5 - 10" rims. i talked to the tire shop about it and there is no safety issue with putting wider tires on narrower rims, its more of a wear issue as the tires cross section will be rounder. he suggested you can compensate for this to some degree with reduced air pressure.
also apparently narrower rims with wider tires helps to keep the bead seated when you air down a lot.

I ran 32x11.5r15 on 15x7 wheels for a really long time - and wheeled the living shit out of them. I never had a problem.

i just got some 33x12.50.15 mounted on my 15x7 just to see how bad it would be and i like it how it is. there is no excessive sidewall buldge and the ride is no different, from what i can tell moving from 10.5 to 12.5

try it to see if you like it, but be prepared to buy new rims if it doesnt work out

I have 33x13.5 on 15x8's, haven't noticed a problem yet, and don't intend on running into any.

They recommend a wider rim because, as fuzzydog said, the middle section is rounder and tread wear is an issue. Just run a slightly lower pressure is all.