Bolt measuremets

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dusdem

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I have a 1972 Plymouth Valiant and I want to change the stock rims. I measured the Bolts and come up with 4.5 They tell me thats not right. Does anyone know if the measurement is 4.5?
 
I think you are asking for the bolt pattern of the wheels which should be 5 on a 4" circle unless somebody has changed out suspension parts. If it is 5 on 4 the lugs will be 7/16" diameter instead of 1/2". The actual lug not the nut. So that means if it is still original the radius from the center of the spindle or axle to the center of one of the lugs will be 2".
 
Did you measure like this?

Bolt Pattern Measuring.png
 
So, I always wondered, why does every other pattern go center to center, but 5 lug goes from center to outside?
I understand with an odd number, stud center to center isn't going to be equal to the circle diameter, but center of one stud to the center of either of the 2 across will still be the same.
 
Last edited:
RogerRamRod said:
So, I always wondered, why does every other pattern go center to center, but 5 lug goes from center to outside?
I understand with an odd number, stud center to center isn't going to be equal to the circle diameter, but center of one stud to the center of either of the 2 across will still be the same.
Click to expand...

Because THAT IS NOT how "bolt circle" is measured. "Bolt circle" is exactly what it implies.....the DIAMETER of the bolt circle. It is from the center of the spindle to the center of the studs for the radius, and X2 for the diameter, and THAT is difficult to measure at least "on the front".

Look at what they are doing in the attachment posted above.......4, 6, 8 bolt are all "straight across" so c-c on opposite studs will give you the "circle." Five lug is not straight across. The measurement method is a "trick" that is close enough.
 
It would be the same or more difficult with any odd number of studs; like 7 or 9 or 11, etc. The chart shows a shortcut for 5 luggers cuz a lotta people have trouble measuring to an unmarked center; and when you double it, you double the error.....
 
Don't worry about it. As far as I can recall, "5" is the biggest odd number of studs you are likely to find. 7, 9, 11, 13 stud wheels would be a real rarity, at least in road vehicles.
 
Oh, it is the bolt circle, not the bolt spacing, thank you. That was easy.
 
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