Compatible Modern Tire Size for 8.25-15 and 7.75-15 Size Tires

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Question:

What is the difference between 8.25-15 and 7.75 -15 trailer tires? Will they interchange on the the rims? Thanx

asked by: Steve

0

Expert Reply:

The tire sizes you mention are considered to be obsolete sizes. The 8.25-15 tire would have an 8-1/4 inch width and a diameter around 28-1/2 inches. The 7.75-15 tire would be around 7-3/4 inches wide with an approximate diameter of 27-3/4 inches.

The closest modern tire size to the 8.25-15 would be a ST225/75-15, available in bias ply load range D as part # AM1ST96, or in radial load range D as part # AM10256 or load range C as part # AM10251. A ST225/75-15 would be about the same diameter but about 1/2 an inch wider than the 8.25-15.

The closest modern tire size to the 7.75-15 would be ST205/75-15, available in bias ply load range C as part # TTWSF20515C or # AM1ST92. It is also available in radial, load range C as part # AM10244. The ST205/75-15 would about the same diameter and 1/2 inch wider than the 7.75-15.

The tires you mention as well as the ones I recommended can all be used on the same sized rim.

Be sure to always keep your trailer tires inflated to the maximum tire pressure stated on the tire sidewall. Under inflated tires lead to heat build-up and premature tire failure.

I have provided links to the tires mentioned above, as well as a link to our Trailer Tire FAQ page.

expert reply by: Mike L

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Answer 1

If you've had offset wheels on your trailer from the beginning then it was by design from the manufacturer and would not be an issue. Switching away from an offset could mean that the wheels/tires end up rubbing against the body of the…

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Answer 2

You should never change the wheel offset on your trailer or use different offsets on tandem axle trailers. Your axles should match, as should your tires. Your wheels can differ in style, but they should not differ in offset. This basically means…

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Answer 3

You can certainly change your trailer tires to a narrower 205mm width as long as your wheels are 6- or 6-1/2-inches in width. These are the only size wheels that can take both 225mm and 205mm tire sizes. Please refer to the linked article on tire…

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Answer 4

Most of the trailer tires will have what is called a zero offset. That means that the direct center of the wheel and tire is measured to where the wheel mounts to the hub face. If you remove your tire and wheel and measure from the back edge of your…

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Answer 5

The suitable replacement for H-78 tires would be the tire size 225/75-15 which is 1.3 inches different in diameter from the 205/75-15 tires. I suppose you could get away with the 205/75-15 to get by in an emergency or temporary situation. However, my…

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Answer 6

Most trailer wheels do have a zero offset to evenly distribute the weight of the trailer on the wheels, however, that does not mean all trailer wheels must have a zero offset. As long as there is enough clearance between the inside of your tire and…

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Answer 7

The 8.25-15 tire would have an 8-1/4 inch width and a diameter around 28-1/2 inches. The closest tire size we have to that in a 17.5 is 215/75R17.5 like the part #TTWP15175 which has an outer diameter when inflated of 30.2 inches. This would make…

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Answer 8

From my research your 7.75x15 sized tires are closest to 205/75-15 and 215/75-15 sized tires. We carry size 205/75 R15 tires like #TR20515D. These are load range D and have a maximum capacity of 2,150 pounds at 65 psi. They also have a higher maximum…

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Answer 9

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 10

To secure the Erickson Horizontal E-Track #EM59150 you need to use the E-Track Backing Plates #e66RR to secure them to the floor. The screws can easily pull out of the plywood especially considering your van will be absorbing a lot of road shock. You…

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Answer 11

Thanks for providing a photograph of your trailer axle sticker. I was able to speak with my contact at Dexter Axle and find out the bearing sizes. You need the etrailer #BK3-300 Bearing Kit. This will get you bearings, seals, and races. At this very…

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Answer 12

Good news, I can help you find a tire for your Sundown Horse Trailer. The 205/90-15 is a close tire size to the 7.00-15. The closest size to a 7.00x15 tire that we offer would be a 225/75-15. One 225/75-15 tire that could work for you is the Kenda…

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Compatible Modern Tire Size for 8.25-15 and 7.75-15 Size Tires

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