Please help me out Tire Gurus!

[cgguy]

Here's the deal. Im running the following rim specs. 18x8 (offset +30) front and 18x8.5 (offset +33) rears on a '98.

I've got a great deal on the following tires. 225/40/18 front and 255/35/18 rear. Is this a good idea? It seems to be the best setup for retaining stock S14 wheel diameter.

Does it make sense to run a thinner sidewall outback? Or will the extra width make up for it? And is 255 going to be too wide on an 8.5" wide rim causing clearance problems with coilovers?

Thanks guys!