Measuring bolt pattern.

I realize this will be a dumb question, but I was just talking to some friends last night and the mention of lug bolt patterns came up. Well I zoomed right in stating that my Maverick's bolt pattern was 5x4½". Fine! My buddy grabbed up a loose center cap and measured hole to hole and it came out to 4¼"! HUH? I know for a fact my car has a 4½" bolt pattern. What in the world is going on here? We measured the same 4¼" right off the lugs too! Did some Fords have a 5x4¼" pattern?

 

5 lug is measured from the center of one hole to the back side of the other, not center to center. There is your 1/4".

 

Measure from the center of one bolt to the outside edge of another bolt two bolts away.

 

The 4.5" is the diameter of the bolt circle. Since, with a 5 lug, the bolt holes aren't opposite each other, you can't measure center to center. Just happens that, for a 5 lug, from the center of one hole to the outside edge of a hole two holes away, is also 4.5".

On 4 and 6 lug wheels you can measure the bolt circle from the center of one hole to the center of the opposite hole.

 

Fantastic! I knew I was doing something wrong! Now I have something to tell my " ignorant " friends! Only kidding! It was driving us nuts trying to figure this out. It's kinda like the way a shotgun shell length is measured after it's been fired. Thanks for the info!

 

Well, I didn't know that. Maybe its measured before its loaded?

 

Quite possible! I know it's measured with the crimp open.

 

OK, at the risk of sounding like a know-it-all, I'll chime in on this one too. I suppose the shells are measured with the crimp open because the measurement represents the length of the chamber, which has to be long enough to take the expanding crimp.