Choosing Trailer Tire Load Range and Size for Safety Margin on 5th Wheel Trailer
Question:
Currently have 235/85R16 tires on 38 ft Big Horn 5th wheel. Toyo 215/75R17.5 are rated for 4800 lbs H rated Toyo 235/85/R 17.5 are rated at 6000 J rated My local tire guy says go with Toyo 245/70R17.5 which are j rated Also 6000 lb. he says they are close to same diameter. I wonder if that’s too much tire? Thanks
asked by: Steve W
Helpful Expert Reply:
Changing to higher load range trailer tires means they will tend to run cooler and this is always a good thing. The highest weight rating we offer for your current tire size ST235/85-16 is 4400-lbs, with the G-rated Taskmaster Provider radial # TTWPRG235R16. This tire has a speed rating M, meaning it is good to 81-mph.
You can decide how much tire you really need by dividing the Big Horn's GVWR by the number of tires on it. For example, the Bighorn 3370EL has a GVWR of 16K. This means that at this maximum loaded weight each tire has to support 4000-lbs. If you typically run lighter, say 15K, then the Taskmaster # TTWPRG235R16 would give you a solid safety margin of 650-lbs per tire. You would not have to buy new wheels is you stick with the current size. Having 2000-lbs per tire safety margin would be nice but may well be overkill.
Moving to a larger tire size is often possible but with that you need to be sure you still have enough sidewall-to-frame clearance, at least 3/4-inch, and enough space above the tire for normal suspension travel, generally no less than 3-inches.
The diameter of your current tire size 235/85R16 tire is about 31-1/2-inches. Width is about 9-1/4-inches. The diameter of a 245/70R17.5 tire is about 31-inches and the width is about 9-1/2-inches. So, in the majority of situations these two tires sizes will be interchangeable.
Products Referenced in This Question
Provider ST235/85R16 Radial Trailer Tire - Load Range G
- Trailer Tires and Wheels
- Tire Only
- Radial Tire
- Load Range G
- 235/85-16
- 16 Inch
- M - 81 mph
- Taskmaster
more information >
Product Page this Question was Asked From
Westlake 215/75R17.5 Radial Tire w 17-1/2" Lynx Aluminum Wheel - 8 on 6-1/2 - LR J - Black
- Trailer Tires and Wheels
- Tire with Wheel
- Radial Tire
- Load Range J
- 215/75-17.5
- 17-1/2 Inch
- L - 75 mph
- 8 on 6-1/2 Inch
- Aluminum Wheels
- Boat Trailer Wheels
- Westlake
more information >
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