Hi, just bought a 1957 Mercury Montclair 2 door today. Has a bad tire so trying to figure out the bolt pattern so I can bring a spare with me. Don't think my winch is capable of hauling that much iron onto the trailer with a flat tire. Looking online one of the old car websites shows it's a 5x5. However, today I actually pressed a piece of paper over the lugs so I could physically measure. Big question is what's the right way to measure a 5 lug pattern? One website shows straight line across the bottom of two lugs then 90 degrees off that line to the center of the lug across, that's Tire Rack. Another said measure center to center then multiply by 1.05. Using the line and 90 degree method I measured 4.75 inches. Using the measure and multiply it's 5 inches. Could probably buy 2 spares but would rather not.
5x5 is the OEM pattern. https://www.jalopyjournal.com/forum/threads/how-to-measure-your-bolt-pattern.1067734/
If you measure from the center of the axle to the center of a stud, that is half of the bolt circle so multiply by 2. The drawing a line across two studs and then across to a stud would work fine if you were measuring a pentagon.... Think about it. 5th grade math here. Sent from my Moto G Play using The H.A.M.B. mobile app
If you draw a 4 1/2" circle and then make 5 evenly spaced bolt holes centered on the circle you will have a 4 1/2" bolt pattern used by Ford and many others. Not easy to measure with a tape measure so you improvise.
The straight line didn't make a lot of sense to me but that's what they're promoting... https://www.tirerack.com/wheels/tech/techpage.jsp?techid=92 My wife complains I have 2 of everything and today I was forced to admit I had both 4.75 and 5 lug spare tires in storage.
lucky the rear end is still in it!that was a popular one for building circle track cars-narrow[59 inch?]5X5 bold circle and a light 9 inch housing.We did run into some with pin holes rusted through,but were worth fixing
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