I have 15" rally wheels on my 66 Chevelle. Is there something on the wheel which will tell you if it is 15x7 or 15x8 and also identify the backspace? If so, where is it? Thanks

Rob

there are letter codes that will identify stock rallys...

Sorry, but I don't know the codes...

I think most 15X8s are apparent due to the spacing of the center... I think they might have the same rear offset as the 15X7, and I know the front is much deeper...

Then again, there are variations, especially if the wheels aren't stock... My 15X8 use the 15X7 trim ring because the stock 8" ring would be too wide...

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"Once you go RAT, you never go back..."
TC #1366
Tony
http://www.chevelles.com/showroom/Quik66.jpg
http://www.chevelles.com/showroom/eng7.jpg

Sorry don't know the codes either, but here's what I would do.

Go to tirerack.com or the website of your tire's manufacturer and find the section width. Remove tire (lay on garage floor) and measure total as inflated section width. Compare this to the tire spec. Remember to expect section width increase of 0.2" for each 0.5" increase in rim diameter.

For instance, if you have a 225/70/15 inch tire it might have a 9.0 section width for a 6.5" rim. Therefore 7.0 inch rim section width would be 9.2" and 8.0 inch rim would be 9.6". This is a pretty indirect method, but you'll be removing the tire anyway to measure backspace.

Now that you have the tire off the rim, measure the backspace. It is pitifully easy. Place ruler on the backside of the tire rim (not on the rubber!) and measure distance to the mounting surface that contacts your hub/brake disc/brake drum (which may not be exactly be the lugnut hole). If you have a 15" rim, a 15" ruler makes this very easy. Otherwise, cut a stick, leftover baseboard, or whatever, as long as it's straight.

jlaf