So I am getting ready for my next road course event and want to get a second set of rims and tires. I was orginally thinking of going down to a 18 or 19 inch rim but choices seem limited. I am not really to concerned about the look since they will just be used on track days. I found a pair of 20 inch rims on ebay that seem like they should fit.

http://cgi.ebay.com/ebaymotors/RVM-SERPENT-20-BLACK-RIMS-WHEELS-JEEP-GRAND-CHEROKEE_W0QQcmdZViewItemQQcategoryZ43960QQihZ011Q QitemZ320115171370QQrdZ1QQsspagenameZWDVW

Can anyone confirm that these would fit over the brakes? They are a real good price, should I be concerned they are too cheap? What about the offset for the rears, stock are 50, will I need spacers?

My next question is what size tires should I run to keep the orginal OD of 29 inches but maximize the width of the tire for grip on the road course? I would like to go as wide as possible but have the same size all around. I was thinking about 255/45 20 . Can some of you tire expert guys chime in with some words of wisdom?

PLEASE PLEASE PLEASE stay away from RVM.

I have their 22's and they had the WORST customer service ever and also sent me bigger wheels than the auction stated and WOULD NOT take them back.

Well RVM responed and stated the 20 inch rims they have will not fit the Jeep SRT8. Seems I am back to nothing. Anyone know of other companies with inexpensive rims, would love 18inch ones but 20s would be ok, that will be strickly used at autocross and road events only?

I've been all through this, and not found anything promising. The real challenge is that you don't have a center differential, and you need tires with the same O/D at different widths, or within 3% max. if you don't want to destroy your driveline.

I think the best you could do is run the stock wheels (which are forged BTW) with 275/40-20 front and 315/35-20 rear. The best suited tires you'll find are probably Vredestein Ultrac Sessanta (my choice) or Michelin Diamaris (the Cayenne GTS Turbo tire, I think)... both of these are DOT tires of course. I haven't found any R-compounds in this size, or the stock sizes; not a surprise, really. The vette people who run in street tire classes seem to thing very highly of the Vredesteins.

Then, you might be able to find cheap wheels in the smaller sizes (or, larger!) for the street and whatever tires fit. You'll also find that changing wheel sizes is a real problem since there is about a playing card of clearance around some of the suspension parts.

If you find out anything interesting here, please let us know.