aftermarket wheel size

[122838B]

Barney says 235-55-16s are a good size for aftermarket wheels and tires and in ton to 17 inchers, a 225-50 will fit while 245-45 might create a width problem. What about 235-55-17s. Would they create a fit problem? The reason I ask is that many of the wheels in the aftermarket now seemto be 17 inches and up.

[Barney Eaton]

I hope someone with actual experience joins this post.

Changing tire size is fairly simple and by going to www.powerdog.com you can compare your original tire size with others. The goal is to keep the same revs/mile (within 1-2%+/-)

The original 215/65r15 on the '88-'90 cars gives 776 revs/mile.

Going to 235/55r16 gives 770 revs/mile...only a .7% difference

Going to 235/55r17 yields 742 revs/mile, a 4.5% difference, that changes your speedometer 3 mph.

You must also keep in mind that the 215 = the fattest width of the tire and on the factory tires that is 8.5 inches. 235mm = 9.25 inches or a increase of .75 inches. Half of that goes to the outside and half goes to the inside. So 3/8 in will not give interferrence on our cars with stock rims.

So the next step is selecting the rim to control where the tire sits on the ground compared to the original. This gets coplicated and I don't have a recommended site that can help with that selection.

Try this site http://www.1010tires.com/WheelOffsetCalculator.asp

[padgett]

Are a number of factors involved but can say that 16x7 wheels with a 38mm offset and 225x60x16s are the largest combination that will go in the front without rubbing somewhere at full lock. 235 would probably be OK with a 46 mm offset (factory wheels).

Aftermarket wheels generally go with less offset than the factory for more inside clearance but this increases the arc the tire goes through and reduces the fenderwell cleanance at full lock. Are also some more subtle issues.

[bigsteviejoe]

I for a long time was looking at 225/50/17 but was told that they are and I agree a little too skinny for rims 8 inches wide. The extra mm is better for rim guard. Plus the diameter is still smaller with a 225/50/17.

If you want to go skinner than 245 if at all possible go for 7-7.5" width, it allows more room for clearence and you have more margin for error if you cant get the exact offset you want.

You'll save $$ and weight going the 16" route.

[padgett]

Funny how times change. When I was a yout, the reason for non-stock sizes was maximum cornering power which required a rim at least as wide if not wider than the section width of the tire. Now apparently you want a rim narrower than the tire to protect the rim from kerbing.

On the front of my Judge I have 225x70x15s on 15x8 snowflakes and consider the rims OK for street but too narrow for competition.

ps I did settle for 15x7s for the 215x65x15s on the back of my Corvair because I could not get the tires to seat on 15x8s & did not care to use explosives. Besides it's a cruiser.

pps the reason for 16x7s on mine was I got a really good deal. Would have really preferred 8s but have no plans to autocross.

ppps had 205x60x15s on 15x7s on my Fiero. Looked nice for the street.