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I think you will find that most LT tires in load range D and E are spec'd similar to ST tires. We switched from 225/75x15 LR-E ST tires (Maxxis) to 225/75x16 LT tires (Michelin XPS Ribs).
If my memory is correct, there was only about 1/2 inch difference in radius (which reduced clearance in the wheel wells and raised the trailer only 1/2 inch). Also, I think the new LT tires were actually rate a couple of hundred pounds higher than the ST tires.
The biggest difference -- the Michelins cost about twice as much as GYM and Maxxis tires. However, it was worth it to put multiple ST tire failures (including Airstream-damaging blowouts) behind us.
225/75x16 LT tires are available about everywhere in many different brands and models, as they are a very common size. We got ours at Discount, but they were also available at Costco and numerous other places. We picked Sendel wheels online, then ordered them through Discount; and had both mounted at the same time.
Because of numerous tire failures on our Bambi, we purchased these through Discount to get the tire warranty. I usually don't get extended warranties on anything, because I think it is just extra profit for the store. However, with our history with trailer tire failures, I thought it was worth the extra price.
We got the extended warranty on the Maxxis ST tires when both OEM GYMs failed. Then, when the belts slipped on one of the Maxxis tires, we got credit from Discount Tire for a free tire, which we applied to the cost of the 16-inch wheels and XPS Ribs. I figure until we actually replace tires on our Airstream because they're bald or weather-checked/dry-rotted, I'll continue to buy the extended tire warranties. Hopefully, these XPS Ribs will boringly dry-rot in 6-7 years, at which time, I will willingly toss them and buy two more.