Recommended Trailer Tires for Maximum Load Capacity and Speed Rating

Question:

I have a non-brand trailer with 15inch wheels and 225/75-15s on which I haul a particular piece of equipment on a regular basis. These are STs and their capacity is 2,830lbs, which as near as I can tell is the highest capacity available in 15inch STs. The problem is that they add up to a combined 11,320lbs and my running weight with the standard load is about 12,000. Naturally, I am destroying tires on a regular basis and this is not only expensive but unsafe. I have come to the conclusion that the least expensive option is to go to a 16inch wheel so I can run heavier duty tires. I currently have 6 x 5.5, 15inch wheels with a 4.25 pilot hole and would go to the same wheel in 16 The most obvious option is the 235/80-16 E-Rate with a load capacity of 3500-3520 pounds, which comes out to 14,000 pounds, giving me about 2,000 pounds of head room. I have two concerns: 1 The new tires would add about 1.25inch of radius, which may cause clearance issues, but I can fix that by cutting off the fenders and welding them back on higher. 2 I dont know which tire brand and model you carry that is best suited to heavy use at about 85 percent of capacity. THATS my question.

asked by: Eric S

Expert Reply:

All 15-inch trailer wheels in your 6-on-5-1/2 wheel bolt pattern are the size 15 x 6. These wheels, shown on the linked page, themselves have varying weight ratings, from 2600-lbs for the Dexstar Conventional Steel Wheel # AM20514 to 2830-lbs for the Sendel aluminum wheel # AM22654.

The reason I mention this is that apart from your chosen tire capacity your wheels themselves may be overloaded. Our resident wheel and tire guru said that any given trailer wheel is more likely to withstand overloading than any given trailer tire but naturally it is best to avoid either part being used beyond rated capacity. An overloaded tire will run hot and this heat is unlikely to harm the steel or aluminum wheel but heat is the single primary cause for trailer tire failure.

I also linked our page for Load Range E radial trailer wheel/tire items in the larger size ST235/80R16.

As long as you can create the necessary clearance for larger tires then moving to 16s is a good plan.

Do keep in mind that other than overloading a tire the other main causes for tire failure are incorrect inflation pressure (either too low or too high) and driving the tire faster than its rated speed. Both of the Westlake tires referenced above are rated for 75-mph maximum (an L speed rating) but we do also have products such as Provider # TA59VR rated to 81-mph (an M speed rating).

All trailer tires, regardless of type, size or load range rating, should always be inflated to their maximum rated COLD tire pressure as noted on the sidewall. It is NEVER appropriate to under- or over-inflate a trailer tire for any reason.