Member
Posts: 17
Location: Loveland, OH | This is a tricky question because it depends on what your rims are rated for psi wise. If your rims are only rated for 50 psi, it won't do much good going to load range D tires. But it won't hurt either. Just keep the pressure at 50 psi cold or less or get higher rated rims. A LR D tire will have a slightly increased load capacity at the same pressure as an otherwise identical LR C tire. How can you tell what your rims are rated for? Sometimes it's marked inside of the rim. Sometimes it's not. My trailer has 14" steel rims rated for 50 psi and load range C tires rated for max 50 psi and a max speed of 65 mph. When I pull the trailer, I air the tires to 50 psi cold and keep my speed at 65 mph or below. My trailer is rated for 7,000 lbs GVWR and the tires are rated 7,280 lbs (1,820 x 4). So this setup is well matched. But I have been towing travel trailers for many years and blowouts are common. I hate not having margin on my tires. Especially if you tow in hot climates. S when I can afford it, I'm switching to alloy wheels and LR D tires. Probably move up to 15" or 16" rims to gain some ground clearance and that allows me to buy LT tires instead of ST tires.Hope this helps. |
Expert
Posts: 5870
   
Location: western PA | IMHO your dealer is doing you a favour with his recommendation to use a "D" range tire. With a reserve load capacity, your tires will run cooler. Over heating from low inflation rates or overloading is the main reason for tire failures. Their carcasses have more plies in their construction, which will increase their longevity when they hit pot holes, rocks, curbs or the edges of the roadway. Remember that your tires' inflation pressure is designated at a "cold" non running rate. When the tires are being used, especially on a hot day, the tire pressures can easily increase by ~10% or more. The rims and tires are designed to handle these higher pressures. Most accessories and systems have a safety margin of over 25%, some as high as 50%. That means that if you put 51 psi of air in a rim marked at 50-psi, it's not going to blow up, and probably won't leak until it's well past 75 psi or so. Even at that rate, the valve stems may be the weakest links and they can easily be swapped out. A "D" range tire will only have to be inflated until it meets the load rating that it is carrying. If it were inflated at the "C" range of 50 psi, it would carry the load and would not be underinflated. At 60 psi, it would provide a higher load capacity and run cooler, increasing its life span. With an over capacity, you don't have to run the tires at their max inflation rates. As was mentioned, at their max inflation, they will provide a stiffer ride when the sidewalls don't flex as much, which on some setups, is about all the "suspension" you will notice. We recently had a poster who changed out the "P" tires on his SUV to truck LT tires. The tires gave him a much higher load capacity, and by running them lower than the max inflation rate, his ride was not adversely affected. In fact he noticed better handling as a result. Remember too, that on each tire is stamped a temperature grade code. They are usually graded with the letters A, B and C. If two tires have all the same load ratings, and one is marked A and the other is a C, the difference is in how the various constructions resist damage from heat build up. The A will last longer and be more resistant to heat damage and failure than the B or C. This is something that should be considered in the purchase of tires, especially those that will be used in long hauls with heavy loads. I would definately choose the "D" range tire, and would remind you of the constant problems noted within this forum, that are associated with Chinese tire brands. |
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