Here's a diagram on determining bolt patterns. Then owner should be able to read tire size for you.
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Determining the Bolt Pattern
The first number in the bolt pattern is the number of bolt holes. The second number denotes the diameter, in inches, of the circle on which the bolt holes sit.
Bolt Pattern - Odd
To determine the bolt-circle diameter on wheels with an odd number of bolt holes, measure from the center of any bolt hole to the point halfway between the two bolt holes directly across from the first. (Example: "5 on 4-1/2" means 5 bolt holes with 4-1/2" measured to a point halfway between the opposite bolt holes.)
Bolt Pattern - Even
On wheels with an even number of bolt holes, measure from the center of one bolt hole to the center of the hole directly across from it. (Example: "8 on 6-1/2" means 8 bolt holes with 6-1/2" from the center of one hole to the center of another on the opposite side.)
Bolt Pattern - Side
Measuring the distance from the center of one bolt hole on the wheel to the center of a bolt hole right next to it can also help to determine the bolt pattern.
If D = 2-5/8", then the bolt pattern is 5 on 4-1/2"
If D = 2-3/4", then the bolt pattern is 5 on 4-3/4"
If D = 3", then the bolt pattern is 5 on 5"
If D = 3-1/4", then the bolt pattern is 5 on 5-1/2"
Hope this helps.