How to Determine Tire and Wheel Size for Spare Trailer Tires and Wheels on a 1973 Winnebago Indian

Published 08/17/2011

Question:

how can i make sure to order the right rim for my trailer. my trailer is a 1973 winnebago indian. the stickers say it has 3500lb axels. it is a 4 bolt pattern and i had some guy at a salvage yard measure one of the rims and he said it was a 14. I dont know how wide it is. is there any markings on the axels or hubs that would help identify the correct rim? I am looking to buy 1 or 2 for spares from you and would like to get the correct size. thanks

asked by: Josh G

Expert Reply:

To verify that it is a 14 inch rim that you need, take a look at the tire size on the side wall of one of the tires. If it is a metric size it will be a number like this: ST205/75-14. The last number indicates the wheel size.

Another common size on a tire will be numeric: 4.80 x 12B. In this example 12 indicates a 12 inch rim.

And it could be Alpha Numeric: B80 x 15D. In this case, 15 indicates a 15 inch rim.

In order to measure bolt pattern, there are a couple of ways you can do it:
1. Use the number of lugs and the bolt circle:

If there is an EVEN number of lugs: Measure center-to-center on lugs directly across from each other
If there is an ODD number of lugs: Measure from the center of one lug to a point halfway between the two lugs directly opposite on the bolt circle. With an odd number of lugs, there is not a lug directly opposite any hole, so finding the circle diameter can be challenging

2. Use the distance between the center of one bolt hole to the center of the bolt hole adjacent to it:

If the distance is:
2-5/8 inches - the bolt pattern is 5 on 4-1/2
2-3/4 inches - the bolt pattern is 5 on 4-3/4
3 inches - the bolt pattern is 5 on 5
3-1/4 inches - the bolt pattern is 5 on 5-1/2

I have included a link to our series of tire and wheel FAQ articles that should help.