Multiple Tire Blowouts

gmw photos wrote:
Cal,
Thanks for taking the time to write out something that seems like a rather complex way of looking at the subj.

I'm not sure what to think of all the details.

What I do know is that I have two trailer manuals, from two different companies here, that say when selecting replacement tires, I can use LT if I so choose.

That's a vehicle manufacturer option and their choice to do so. However, do they tell you how to go about insuring the switch to the LT tires can be accomplished and stay within the acceptable tire industry safety parameters?

That's good enough for me. I'm not equipped to argue the semantics of of "approval" vs "a long list of federal certifications".

I like LT tires on my trailers. I have used them with much luck. I've used ST tires also. Not so much good luck with them.

warm regards, gw

ps, I do make sure I am choosing replacement tires that have load rating that is in excess of the actual load being carried, and also is in excess of the axle rating. I never run with overloaded tires or axles. My travel trailer has 7600 pounds of LT tire capacity, with 3600 actual pounds on the axles.
My small horse trailer has 8400 pounds of LT tire capacity under an actual load of no more than 5500 axle pounds. Etc., on my other trailers. This has worked well for me with LT tires.

It did not work well for me with ST. For the first year of my two newest trailers ( 2016 ) I tried getting by with running the factory OE ST tires. One failed on the horse trailer ( Provider brand ) and one failed on the equipment trailer ( BCT brand ). I don't know why they failed. They were inflated correctly on the morning of failure in both cases. I didn't agonize over either. Both trailers now have LT, and have run without failure since then.

The reason ST tires are so hard to replace with LT tires is load capacity. Here are a couple of examples. The ST225/75R15 LRE has a maximum load capacity of 2830# to match that load capacity with a LT tire will almost always require new 16" wheels and tires. A lot of RV trailers do not have the axle spacing for the taller tires. The ST235/85R16 LRE has a maximum load capacity of 3640#, the LT235/85R16 LRG has a maximum load capacity of 3750# and is one of the few fitments that will work by going up with the available two load range increases and using wheels that will support the 110 PSI necessary to gain equal load capacity from the LRG tires.

p.s. providing tires for the actual load carried is not from the FMVSS standards and is not applicable for RV trailer tire fitments.