[marc]

A) Is there a benefit to having a wider rim - for example, you want to run a 265 width tire. Is there a benefit to having a 9 inch wide rim as opposed to an 8 inch wide rim, assuming it will fit on both rims ?

B) Effects of staggered setups - what effects will running a 17 up front and 18 in the rear have, assuming the basic circumference of the tire is preserved (like a 245/40/17 up front and a 275/35/18 in the rear). Is it better to go with one diameter all around?

I didn't ask these questions in the RX-7 forums cuz they're a bunch of elitist road racers. My main problem is, the ass keeps sliding around through 3rd gear. I want to kill this oversteer and instability and maybe venture into understeer land.

Currently I'm on Enkei Evoltion RS 3-piece rims, 17x7, running 235/40/17 Goodyear Eagle F1s in the front and rear. They aren't cutting it with 420 whp on tap.

 

[many]

420 whp wow man thats a lot.
Well having a wider rim means that the tire will not baloon on the sides, this is crusieal fo a good contact patch to the pavement! You should always check the recomended manufacturers numbers(on how wide of a rim that specific tire will need)
On the stagered effect the new Elise is running on 17 up front and 18 at the back (if i remember corectlly), I heard theat this set up the end has less tendency of wobbling ,Meaning that the side walls remain stiffer !

 

[Dragncrosmember]

I don't see a problem with going one wider in the rear. Just remember to try and stay close to the same overal diameter. ie. skinner 40 series tire up front and a wider 35 series tire out back.