ST Tire "Plies" Question and a PSI Question

BFL13 wrote:
If STs are to be kept at full pressure even when the weight doesn't require it, but LTs' pressure is adjusted for the weight, then it is more likely the LT would not be at full pressure. So that would be fine for the weight but not so good for the sheering?

Should the advice to be at full pressure despite the weight also go to LTs when mounted on trailers to help with the sheering?

If by sheering you mean throwing their cap, I only know of a couple LT's the people use on trailers that seem to do that. The Goodyear G614 had a history of that in the 2006-2007 time frame and the BFG Commercial TA and twin Uniroyal Laredo HT had a history of problems when used near its max load. Many ST tires however over the years have experienced that over the years. Mission, Duro, Marathons, Tow Max xxx and yyy have had early failure issues not just of RV trailers, but on horse, boat and other trailer types.

My trailer came OEM with optional LT235/85R16E china bombs made by Kenda Tire. The Placard lists 65 pounds inflation, which I believe was for the standard 15" ST tires. Within the first year Kenda gave me 110 dollars x 5 to remove their tires and have the tire shop destroy them.

I installed Michelin XPS Ribs and ran them at 65 inflation. The trailer has plus or minus 10K of the axles depending on the trip. After a couple years I measured a slight more wear on the outer edges of the new tires. So I upped inflation to 71 pounds. Those tires were in service for 6.5 years on the trailer and around 45K miles. I sold them on CL for 200 for four of them with 60-65 percent tread left and installed Bridgestone Duravis R250's in the fall of 2011. I run the R250's at the same 71 pounds inflation and they are wearing just fine.

So for trailer service I would say to use what the inflation table says plus 5 or 6 pounds to account for the sway of a tall trailer. I also think that because either one of these two choice preform great of fully loaded 6K axles at 80 pounds inflation, then with 5,200 pound axles you do not need full inflation.

So I have a 10 year history of use of LT tires on the same trailer. I tow with confidence without spending all my time watching my mirrors.

My friend had a similar size Montana for a number of years that came with General or some other poly carcass LT and his placard stated 80 lbs inflation. He had one fail and tear up the side of the trailer. That help convince me that steel ply carcass LT's on a trailer are the only way to go.

My earlier 26' 5th wheel had 15" LRC Goodyear Marathons and I did not have any trouble with them in 7 years of use/ownership. I however used that trailer only in the State of Washington for local camping and it was stored in a garage when not used. I did not track mileage but maybe 10-15K in those 7 years. I think the tires were made in Canada. In retro spec I was dumb and lucky!

Chris