Bolt Pattern (stupid but gotta ask)

[Del72Chevy]

I know most of you will think this is a stupid question but I have to ask. I have a 72 short bed and I was under the impression that the bolt pattern for the 5 lug was 5 on 5" I just happened to put a stick rule on the studs on my rear axle and center of stud to center of stud is 4.75". I know you have to measure across the center to the other stud and not to the stud right next to the other. I know that much but why am I getting 4.75 and not 5". I was curious and grabbed one of my front rotors and it measured the same 4.75". Am I goofy or what?

[geezer#99]

No you're not goofy. Well maybe a little. LOL!!!
Measure from the outside of one to the centre of the second one around. That works.
Or centre to centre is 2 15/16 for side by side studs= 5x5
2 13/16 is 5x4.75

[lolife99]

Here you go,...

[GCncsuHD]

As mentioned, you cannot measure center to center on 5 lug patterns, usually measuring from the edge of one to the center of the one across gets you close enough for old stuff....but with all the metric patterns out today like 5x115 that is only 0.03" larger than 5x4.5", 5x120 which is 0.03" smaller than 5x4.75" and so on that doesn't get it close enough anymore. Heck there are probably 20 different lug patterns out between 5x4" and 5x5.5" now.

For your case though it should be 5x5" unless redrilled for 5x4.75".

[Del72Chevy]

Thanks for the info everyone
Posted via Mobile Device

[100%Chevy]

The lug patterms are based on an imaginary circle the is the center of the lug bolt pattern.
4,6 and 8 patterns are directly across from the opposite lug.So,measure from the centers.
5 lug holes aren't directly across from the opposite lug,so even though it's a 5"pattern,it won't measure out center to center.
Same for any odd number of lugs.
Mike./