sh410 wrote:
Another interest item is that TT with 3500# axles are fitted with Dexstar 15x5 inch steel wheels that have a max load rating of 1820# with a max psi of 50# and are typically mounted with ST205/75R15 C rated tires of 1820#. The next size up are 15x6 inch wheel with a max load of 2050# (?) and max pressure of 75#.
There are not many choices for ST205/75R15 D rated tires of #2150 at 65psi, maybe because there aren't many buyer especially with RV mfgs propensity to fit the minimum (or even less) tires and subsequent buyer buying the same tire that came on on their trailer. Those tire brands that do sell the D rated tire call for a 6" rim.
It makes it very hard for the average consumer to puchase the proper tire for their RV and not all tire dealers are not willing to get into this discussion.
Very frustrating.
Another choice would to reduce that load on the trailer from the GVWR to achieve the 15% safety margin.
This thread has been full of great info esp. CapreRacer, Tireman9 and FE. and has lead me to a better uderstanding of how complex it is at least in this area of RV tire purchase, load, pressure and speed ratings. Thank you!
This is where a forums accumulation of experienced folks (not just 6-8 years pulling a RV trailer or two several times a year) that has been in that type of circumstance many many times and found a better tire for the job can give the trailer owner options if the owner is willing to listen.
Todays RV trailers can have up to 6k and 7k CCC. That means a 10k dry GVW and a 16000-17000 lb GVWR.
My current trailer has a 11200 lb GVWR with 5200 lb axles. The trailer axle weights run from 9000 lbs to about 9400 lbs for longer trips (actual scaled weights). My LT215/85-16 E at 2680 lbs gives me 10720 lb of capacity and has plenty of reserve capacity.
Again, figuring another 15 percent of capacity above my trailer 11200 GVWR would put the trailers tire needs at around 13000 lbs.
IMO lets be careful about a one size fits all with a 15 percent above the trailers GVWR recommendation. It doesn't make cents or sense for many folks.
