My '94 Q45 rear tires are worn out , and my budget doesnt allow me to buy new ones. But I have four extra rims with new tires on them, ( not Infiniti), but they are smaller 15 inchs tall 6 inchs wide. The stock ones on my car ar 16 inchs tall 7inchs wide my numbers may be off a little. My Q. is would it be hard on my diff. end of car to use smaller rims. I expect to loose some traction because they would not be as large, but I have no traction any ways right now with bald tires. Thanks for any help.
Modified by Fred D. at 9:48 PM 3/26/2006

90-96 Q45 oem wheels are/were 15 x 6.5" suitable safe sizes are 215/65/15, 225/60/15 and 235/60/15.

Since wet braking performance [from 50 mph] is very important look at tire rack test where you can see that some cheap/mid priced tires in these sizes take 112+ feet to stop and something like the Michelin Exalto AS can do it in 95 feet on the same test car. 17 feet [15%] is significant when you might rear end another car or run off the road.

$50 vs $90 [215/65/15]

intrestein[QUOTE=Q45tech]90-96 Q45 oem wheels are/were 15 x 6.5" suitable safe sizes are 215/65/15, 225/60/15 and 235/60/15.

Since wet braking performance [from 50 mph] is very important look at tire rack test where you can see that some cheap/mid priced tires in these sizes take 112+ feet to stop and something like the Michelin Exalto AS can do it in 95 feet on the same test car. 17 feet [15%] is significant when you might rear end another car or run off the road.

$50 vs $90 [215/65/15][/QUOTE intresting. so want is the braking performance change to 18's or 19's? Just curious. I have 20 in rims and I will be investing in some 18's when money is avail.

Typically braking distances increase with heavier wheels and tires assuming the compounds are equal.

Braking distances are a function of LOADED CAMBER and toe......why you make sure the static camber doesn't exceed [minus - 0.7 degrees]. AS it goes more negative 0.8 degrees per inch of front end dive.

Not sure that equal compounds in the larger sizes would be any better probably worse. Once you get past 16-17" all about looks and brake rotor fit, not necessarily performance.

I could be wrong but tire rack hasn't tested many 18-20" and the best I saw was 93 feet wet for an 18"..........compared to the 95 feet in 15"

Thanks Q45tech, good info. I will buy new tires for my stock rims, and I'll note the braking distance(if rated). I know they have to be H speed rated also, because of the Q's ability to reach such high speeds. I like the incerdible level of thought in the Q's design.