Tires on New Trailer

To answer the OP's question, probably for most companies.
For me, there is no reason to go with LR D's. I have over 1000lbs. reserve.

Most TT come with under rated tires, Heat and speed are tire killers, upgrade your tires as soon as possible, if C's go to D's ..

get them off and buy some good tires. Also speed is a major cause of blow outs

ROLL TIDE

I also have no problem running load range C tires. I don't have my trailer loaded to the max and don't run max psi but knock on wood, haven't had an issue yet. My casita, then a hi-lo, and now my Lance all run on load range C.

Maybe my world is a bit different, but on 3 different TT's, I used the factory installed tires until one of them showed signs of fatigue. First trailer, never changed them. Originals tires traded with the camper. Second camper, I ran the originals 4 years. They started showing signs of dry rot. Third camper, two years on the road when one tire tread was wearing very uneven. But it took 2 years and thousands of miles too. Swapped out all 4 at the same time, even though the other 3 looked good.

The choice is yours if you want to swap them out or not. If you keep them inflated to the max, inspect them VERY often, and at the first indication of anything unusual, then swap out all 4 at the same time, why not give them a few miles first? BUT! To each his own.

About the tire rating, others above stated it quite well with the tongue weights and such.

Tongue weight on average is around 12-13 percent of the actual weight of a TT. If the actual wt. is close to the GVWR, the tongue wt. would be approx. 6700 lbs. I would suggest a cargo weight allowance of 1,000 lbs on top of the dry wt. which would be 6575 lbs. This would mean that the actual wt. on the axles is likely around 6600 lbs. Load range C ST tires have an 1820 max. load capacity rating (at 50 psi) - 3640 per axle. The tires would therefore be loaded to 6600/7280 = 91 percent (9 percent reserve load capacity).

It is recommended that ST tires have a reserve load capacity of 15 percent min. See comments from a tire engineer at RVtiresafety.net. There are no legal requirements for the amount of reserve load capacity and RV manufacturers can get away with loading tires up to their max and it is common for them to do that. Not having a min. of 15 percent reserve load capacity is increasing the risk of a blowout. When we bought our current TT, we ordered the optional Goodyear load range D tires and have about 30 percent reserve capacity and have not had a single issue to date and are now on our 4th season with them.

A TT can also weigh more on one side, usually due to a slide out. Going to a scale would be a good idea so that an owner knows where they stand on weights.

The axles on that Trail Runner would be loaded to approx. 96 percent of their 3500 lb rating. This is also not very good and increases the risk of bent axles. Again, no legal requirements for max. loading.

With ST tires, it is important to observe the rules specific to them - never tow over 65 mph, never tow overloaded and never tow under-inflated. This will help a LOT with preventing a blowout and with maximizing tire life.

C rated tires-
RV manufactures put the cheapest tires for the purpose of profit:( Throw away those C load range tires. Look for at least a D rated tire or preferably a G rated tire. Blow outs will cost $$ for tires and for the damage to your trailer.

Tire Max Load Rating is same as or more then trailers axles.......

Remember-----
Trailer tongue weight is part of trailers GVWR BUT is not carried/supported by trailers axles/tires. Tongue weight goes on tow vehicle

SO YES tires are marginal but they cover the axle weight. Axles are probably rated at 3500# each for 7000# also.