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Replacement Trailer Tires for 15 Inch Wheels to replace 7.00-15 Tire Size On A 15X5.5 Wheel


I am about to order 4 of your trailer tires Karrier ST225/75R15, load range D your 10256 I believe, and I have TWO questions. my rims are 15x5.5 6 bolt EZ Loader on which Ive been running various brands of 700x15 bias ply LT tires for many miles and yrs with mixed results. Will the above tires fit well on these rims? I recognize the height difference, its the rim width I am concerned about. Secondly, regarding inflation pressure, when I leave WI for Key West each Dec, the temperature is generally between -20 and +30F. By the time I get to S FL temp is generally in the 70s. Given that tire pressure increases about 1 psi for each 10 degree rise in temp, my tire pressure would be roughly 72 psi in FL if I start out from WI with cold tire pressure at the recommended 65 psi. But if its -20 in WI and 80F in FL, the tire pressure in FL could be 75 psi! Is this OK? i.e., all tire mfrs say set tire pressure when cold, but how cold is cold?! Or are all tires built to handle a 10+ psi increase on the road? Will greatly appreciate your thoughtful response to these questions.

Expert Reply:

The Karrier ST205/75R15 Radial Trailer Tire, # AM10244, will fit on a 15x5.5 inch wheel. It has a maximum load rating of 1,820 lbs. at 50 psi and an overall diameter of 27.3 inches. The overall width is 8.1 inches.

I would not recommend installing the Karrier ST225/75R15 Radial Trailer Tire, # AM10256, on a rim width of 5.5 inches. The minimum rim width for that size tire is 6 inches. If you try to squeeze that size tire on a narrower wheel than what is recommended, it will cause the tread of the tire to not lay flat, will wear like an overinflated tire, and it may not seat on the rim properly.

If you want to stay with the ST225/75R15 tire size, I do have the Karrier ST225/75R15 Radial Trailer Tire with 15 Inch White Wheel - 6 on 5-1/2, # AM32664. This is the same load range D tire on a 15x6 white spoke wheel. This tire has an overall diameter of 28.4 inches and an overall width of 8.9 inches.

On the inflation question, tires are built to withstand a lot of abuse. Lower air pressure is more of a problem than higher air pressure. The increase of 10 psi in the tire pressure would not cause a problem if you will set it to the correct pressure when arriving in Florida. There would be more of a problem if temperature change would happen faster (like within hours). Your trip is probably spread out within a day or two.

The best thing to do is set the tires at the maximum tire pressure when you are leaving Wisconsin and as you are traveling and the temperature is increasing, check the tire pressure and set accordingly.

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Thank you very much Jeff, you responded very thoughtfully and knowledgeably, which has not always been the case with others recently. After reading in several travel trailer forums this morning that ST rated radial tires often fail prematurely, (granted, in some cases due to overloading &/or inadequate inflation pressure) I've pretty much decided to replace my four Liberty LT 700x15 D tires (2 of which are beginning to fail after 3 yrs and 13,000 miles. And yes, they are Chinese made, but precious few LT or ST tires aren't these days) with another set of LT tires. Given your comments about rim width, I'll stick with 700x15 size to accommodate my galvanized steel EZ Loader rims. My 25' boat, with full gas and water tanks and provisions for living aboard for 3 mos (yeh, it gets a little snug by the 3rd mo!), weighs about 3 tons, the trl one ton, for ~8000 lb on the 4 tires. I know Load Range D should be adequate, and is what I've always run, but is there any reason not to go with your Kenda 700-15 LT load range E tire (K391M)? One final question; I've never had my trl wheels balanced. Should I?

asked by: Bruce J

Expert Reply:

Glad I could help. I would recommend the Load Range E 7.00-15 tires. This tire has a maximum load capacity of 2,376 lbs. at 70 psi. I looked up a Load Range D 7.00-15 tire and it showed a maximum load capacity of 2,156 lbs. at 60 psi. Any extra load capacity will help.

I would recommend to balance all tires and wheels. Every wheel and every tire have a low (light) and a high (heavy) spot. When you balance the tire to the wheel you are using weights to even out the high and low spots. This will help with tire wear and ride smoother on the trailer.

Also, remember to always fill the trailer tires to the maximum tire pressure.

expert reply by: Jeff D

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