What is Current Tire Size to Replace A78-13 Trailer Tire

Question:

Are you able to cross-reference a discontinued tire? Towmaster A78/x13 ST. I believe it may be ST175/80x13. What does 5 on 4 1/2 mean for bolt pattern? And 3.19 for pilot diameter? Does a tire and wheel combination include valve stems and balancing? Thanks

asked by: Dan W

Expert Reply:

You are correct, the older tire size of A78-13 is the current size 175/80-13 like the # AM31994. The 5 on 4-1/2 inch bolt pattern is the wheel bolt pattern size that the holes of the wheel have to mount up to the trailer hub. Not all wheel bolt patterns are the same but if the trailer has a 5 lug bolt pattern there's a very strong chance it has the 5 on 4-1/2 bolt pattern.

The 3.19 inch pilot diameter is the center hole diameter of the wheel that fits over the bore of the hub. Most trailer wheels with a 5 lug bolt pattern have this pilot diameter and in general is not typically a big factor to consider as most wheels are made with larger pilot diameters that needed to fit the hubs.

expert reply by: Jameson C