What Replacement Tires do I Need for My A78-13 Boat Trailer Tires?

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Question:

Hello, I need to replace the tires off my boat trailer. They are old tires, with the markings of A78-13. What is the modern equivalent size? Ive found varied information on line. From ST175/80-13, to 175/70-13 I think the difference is the overall size of the tire. The current tires come very close to the metal fenders. Are the new tires going to be too big and cause issues rubbing or even getting back on the trailer? OR am I going to have readjust my fenders? OR should I go with a car tire?

asked by: Sam S

1

Helpful Expert Reply:

The new equivalent of tire size A78-13 is 175/80-13. This is the exact same size, so there should not be any interference at all with your fenders that fit the A78-13. I went ahead and attached a FAQ article and table that shows this translation.

As far as using passenger car tires, we strongly do not recommend this for a couple reasons. Firstly trailer tires have stiffer sidewalls and do a better job dealing with vertical loads when hauling. Also, since trailers do not have turning axles, car tires have different cornering nuances than trailer tires.

For a great replacement tire for your boat trailer, I recommend the Kenda ST175/80D13 Bias Trailer Tire # AM1ST51.

expert reply by: Bob C

1

Answer 1

In height or total diameter, a 185/80-13 and 175/80-13 like part #AM1ST77 only differ by about 5/8 of an inch. The 185 would have a diameter of 24.65 inches while the 175 would have a diameter of 24.02 inches. The section width, or thickness of the…

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Answer 2

The tire size you reference, size 5.30 x 12, is compatible with a 12" x 4" rim. The wheel I recommend is Steel Mini Mod Trailer Wheel, #AM20151, as long as your trailer uses wheels with a 5 on 4-1/2 bolt pattern, I have included a FAQ…

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Answer 3

Here is a list of the wheels we have which will fit the Kenda Karrier ST185/80R13 Radial Trailer Tire #AM10208 with a 5 on 4-1/2" bolt pattern. Please let me know if your hub uses a different bolt pattern. Aluminum Hi-Spec Series S5 Trailer…

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Answer 4

First, if a tire starts with a P like your P165 tires that indicates that they are passenger vehicle tires and should not be used on a trailer. This is because trailer tires are built with a thicker sidewall to handle more vertical load and passenger…

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Answer 5

The two tire sizes you have are similar but they are not the same. The 215 tire size is slightly larger in diameter and in width. You would want to go with a new wheel and tire in the size of ST205/75R14 like the part #AM32153 to match that size. The…

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Answer 6

Any tire, when there is a load on it, will flatten out a little. The key with trailer tires is to always make sure they are inflated to the maximum psi rating as indicated on the tire. If the tires are holding pressure under load and they are not…

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Answer 7

With the exception of the Goodyear Endurance line of trailer tires, you should always air trailer tires up to the Pressure stamped on the sidewall of the tire as that is what the tire was designed to be run at. Since trailer tires have a different…

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Answer 8

For a B78-13 trailer tire, the closest match we will have will be a 185/80-13. We have numerous tires and tire and wheel combos in this size and I have included a link to them for you. All of the wheels have the 5 on 4-1/2 bolt pattern like #AM3S331…

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Answer 9

A ST175/80-13 size tire is the correct replacement size for your existing B78-13 size tire. We offer a number of tire and wheel combos, like #TA43RR, as well as tire only options, like #TTWTD17513C, in this tire size. For your 2,500 pound capacity,…

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Answer 10

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 11

The difference between an load range C and load range D tire in the same size is the capacity and psi rating. The two tires will still have the same dimensions and fit on the same wheel. The D rated tire has a higher capacity. For a ST175/80D13 like…

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Answer 12

Load range B trailer tires are going to have a lower capacity than C load range tires. Basically that, psi rating, and the ply rating are the only differences. A higher load range tire would last a little longer than lower load ranges of the same…

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What Replacement Tires do I Need for My A78-13 Boat Trailer Tires?

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