How is lug pattern determined? I know you count the number of lugs, but how do you measure the rest?

Thanks

 

The size is the # of lugs, then the bolt circle of the studs.
Example: 5-5.5
5 lugs on 5 and 1/2 in circle

Randy

 

I have a handy tool from one of the aftermarket wheel companies (as far as I remember). It is a hard plastic ring and has all the typical patterns (i.e. 5 x 5 1/2, 5 x 5, 5 x 4 3/4 and 5 x 4 1/2), meaning that there are 4 x 5 holes and each pattern is offset from the other one so that they all fit on that ring. In order to find out what your car / truck has just take a wheel off and try the various patterns until you find the one which fits (i.e. slips on). The same thing can also be used when trying to find out what a wheel has. Just align the holes of the tool and the wheel (best from inside). I guess such a tool can easily be homemade out of cardboard. I could e-mail you a photo of the one I have.

 

Here's a nifty way to determine the bolt circle (BC) dia. on 5 lug wheels, drums and axles. Measure the distance between centers of the 1st and 3rd bolts or holes. 3-3/4" = 4" BC, 4" = 4-1/4" BC, 4-1/4" = 4-1/2" BC (Avg. Full Size Ford and Mopar cars), 4-1/2" = 4-3/4" BC, 4-11/16" = 5" BC (Avg. Full Size GM Cars) and 5-3/16" = 5-1/2" BC (Full Size Ford, Jeep and Dodge PUs). I carry this chart in my wallet all the time just in case I run across some wheels that strike my fancy and I want to know if they'll fit any of my vehicles.