Si Im having a hard time finding the right size wheels for my 87 Iroc. Im looking for 16x8 wheels. The problem is finding the correct offset and backspace. I can find the fronts with the correct 0mm offset and 4.75 backspace but a real tough time finding the rear +16mm offset and 5.25 backspace. I am going with the original tire size 245/50/16 and found the tires easily. Can I just go with the 0mm offset on the rear and use a spacer to get the 5.25 backspace? Im about ready to just get some refurbished original rims. However I have something else in mind. Any suggestions? Thanks much, Pete sorry if maybs I had missed a post on the forum about this already.

 

No, you cant. Spacers will not change your rim backspacing. I think you are thinking about the numbers incorrectly or backwards. Offset and backspace are the exact same thing, its just a different way to measure. Offset is the difference from the wheel mounting face as compared to the centerline of the rim. This is more difficult to measure by hand. The easier way to measure is called backspacing. So backspacing, is simply a measurement from the wheel mounting face to the inside lip of the rim. The more positive the offset or the greater the backspace is, the more the wheel center is pushed out toward the outer lip of the rim. This in turn positions the wheel deeper in the vehicle wheel well. (Front wheel drive vehicles will usually have more of a positive offset as compared to RWD vehicles).

In your case you are wanting to run a 16X8 rim. 0mm offset results in a 4.5" backspace or half of the rim with (when you measure outside lip to outside lip a 8" rim it actually measures 9". This is on the front. The rears have a higher offset, which means the rim is actually pulled further into the vehicle. This increases fender lip clearance, but decreases the inner clearance. In your case if you ran the front rims on the rear, the wheels would stick out farther then the original rear rims. If you add spacers, you would be compounding this effect making it worse. You may be able to run a 0mm offset on the rear without any issue.

If you could get a 16X8 rim, 0mm offset, try it on the back and see how your fender lip clearance is. I have a set of 17X8 chrome wheels and I believe they are 0mm offset on all four corners. I actually havent measured them, but there are no special markings front or rear and the wheels seem to stick our a little farther then stock and I know one I checked was a 4.5" backspace. Make sure a 0mm offset will work on your vehicle before you order.

I included 2 pics, one is stock wheels, the other is the 17X8 chromes. You may be able to see the difference I am taking about but I know the pics are not the greatest. The 17X8's only moves the wheel 3/4" outward.

 

To put it another way, the aftermarket 17X8" rim with 0mm offset puts the tire closer to the fender lip then the stock 16X8" rim with +16mm offset. How close you ask? About 16mm closer.......

 

Awesome info! Thank you so much! Years ago my original rims and tire were stolen and I went with some AR rims and 60s instead of 50s for tires. Huge mistake! Im going to get new wheels and The BF Goodrich comp 2s. Alot of websites have the vehicle fit check for wheels and of course they always come up as not fitting. Yes I was a bit confused with the offset and backspace. Thanks again for the info. Your Z looks like mine!

 

First, you dont need to have different backspacing for the front and rear when using 16" x 8" wheels - you can use 4 OEM fronts and easily rotate.

Second, 16" wheels are unfortunately becoming obsolete - just look at how many tires are available in 245-50-16 and you see what I am saying. Many aftermarket brake kits have zero chance of fitting under 16" wheels also - limiting upgrades.

That said, you can get OEM 16" wheels for a good price as many have upgraded to 17" and larger.

 

Yes I have noticed that! Thanks for the good info! I appreciate that very much! I have some AR wheels in mind. I still have the original brakes for now.

 

Word of advice - if you are going to order them new and there is a 17" version, go that route. There are dozens of 245-45-17 tires out there, but about 8 245-50-16 sized one these days, plus brake upgrades should fit.

 

Thanks, I'm just starting to look at wheels now probably buy within the month. Good advice.