I currently have 14 in wheels on my 68 Chevelle and would like to go to a 15 inch. This may sound like a dumb question but how do I measure the lug nut ratio? I've seen internet auctions that either say unilug or 4.75 inch bolt circle, etc. How do I know what is appropriate for my car? Thanks!

All chevelles wheel bolt circle is 4.75 in. As far as width, back spacing and other measurements, due a search for wheels and tires.

positioned to look like a cartoon figure with the top hole located at the top representing the head. the two arms and legs at 2, 10 5 and 7 o'clock. wasn't that fun? anyway measure from the 12 o'clock center of the hole to the 5 o'clock outer diameter. this will give you the 4 3/4 measurement. kinda wierd eh? the summit and jeggs illustrate.

Thanks for the quick info. So you simply measure straight from the center of the 12 oclock hole to the outer edge of the 5 oclock hole? Also, one more question if I may. What does backspacing mean? I've seen the term "4 inch backspacing" Thanks again.

What does backspacing mean? I've seen the term "4 inch backspacing" Thanks again.


It's the distance from the outer part of the rim to the wheel mounting surface.

Thanks again! You guys are great! So if I were to remove a wheel and lay it face down, place a straight edge across the top of the rim, and then measure from the surface in the center of the inside of the wheel to that straight edge, that would give me my backspacing meassurement?

Yes sir =)

Excellent! Now, I have seen 2 choices but don't know which ones to go with. One set are for 15x7 with a 4-1/2 inch backspace and the other is the same size with a 3-1/2 inch backspace. I'm not sure what backspace I currently have cause I haven't measured them yet, but am I correct in assuming that the 3-1/2 inch backspace will pull the wheel further out?

You got it now!

Great! Now, one last question if I may and I'll leave you guys alone. What would be the widest tire I could put on a 7 inch wide rim? I've been told 260's would be the max give or take depending on the brand. Is this correct?