What Size Trailer Tires Will Replace B78-13 Trailer Tires

Updated 03/01/2012 | Published 02/29/2012

Question:

will st 175/80/13 replace my old b78/13/st

asked by: Dave T

Expert Reply:

A trailer tire size 175/80-13 will replace either an A78-13 or B78-13 trailer tire.

A 175/80-13 is going to have 3 load ratings: B at 1,100 pounds at 35 psi, C at 1,360 pounds at 50 psi, and D at 1,610 pounds at 65 psi. This size will have a diameter of 24.1 inches. This tire size will fit on a 4-1/2, 5, or 5-1/2 inch wide wheel.

If you choose tires rated higher than your axle, you still have to go by the axle weight capacity. If you choose tires rated lower than the axle capacity, then you need to go by the tire capacity. I have included some links to tire FAQ articles for you.

expert reply by: Michael H