How exactly are wheel bolt patterns measured? And are there basically a few common sizes?

I bought a car dolly last spring that has 14 inch wheels. It came with a spare tire, but while the bolt pattern is the same, but the wheel is a 15 inch, so it doesn't fit.

I was going to see if the bolt pattern is the same and keep the spare for my single-axle trailer. It's a slightly different tire, but a 15" wheel, so it'll do in a pinch.

But now I need to go find a rim & spare for the dolly, so I need to know what to ask for without hauling the thing in someplace. both are 5 hole rims, but bigger than the Fiero.

Thanks,

Andy

Wheel bolt patterns are measured across the pattern. For example, a 5 bolt pattern would be measured as the distance (from stud center to stud center, I believe) along any red line in the attached image.

There's a whole lot of different patterns out there, not really one common one. 5x100, 5x115, and 5x114.3 are pretty common for 5 lug wheels, not sure about the most common patterns for 4 lug wheels.

[EDIT]
Allright, you said it was a 5 lug and larger than the Fiero pattern, so its probably either 5x115 or 5x114.3. The 5x114.3 pattern is actually measured in inches, which is why it comes out being a weird number in millimeters, it'll be 4.5 inches.
[/EDIT]
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Nick www.naskie18.com AIM: Naskie182010

[This message has been edited by naskie18 (edited 11-04-2003).]

most trailers are ford patern sized
a dolly is most likely the same as a trailer
btw the wheel on a trailer are usualy reversed
in offset [inside out] so a cars wheel don't fit [lugs on the wrong side]
anyway look at a boat or trailer store for a rim as they are all the same patern mostly

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Question wonder and be wierd
are you kind?

IIRC: 5x4.5, 5x114.3 and 5x115 are the same pattern, but people call them different things....

Thanks for the help guys. The trailer and dolly are definitely different patterns, so my idea won't work. But I'm on track for getting spares anyway.

And Ray...thanks for pointing out about the offset. You're exactly right, but I wouldn't have thought of that.