Quote:
Originally Posted by Tireman9
OK Here is kind of my overview of tires.
1. The basic format for load capacity is Size (air volume) x PSI x K
2. The "K" is supposed to be a factor that relates to the tire service. If a tire is normally run with a 25% Reserve Load (to account for occasional low inflation or high load) on the improved highway for 3 to 5 years, you might have a high K factor like 1.1. On the other hand, if a significant portion of the population of tires will be operated under-inflated or overloaded and you want 10 years life then the k should be a lower value like maybe .80. But what happens when the vehicle design imparts excess belt stress sometimes 24% higher than seen on normal motor vehicles? The K factor should be reduced significantly. Maybe even 24% to 0.65
2. The RV industry lobbied long and hard to not upgrade the durability improvements that were placed on P and LT tires in 2002. Why? They didn't want to spend more on tires. DO they care more about their bottom line than you having no tire problems? What do you think?
3. The ST load formula was based on a MAX speed of 65 with normal highway speed of 55.
4. Given that the RV trailer travels at the same speed as the tow vehicle, why would you expect people to slow down when the strong engine can easily pull at 80 mph?
5. What is the difference between an LT tire and an ST tire today? They both travel at the same speed on the same roads. The LT only needs to last 4 to 5 years but the RV tire does not wear out till 10 years + in many cases.
6. Under what logic would you expect a tire with the letters "ST" on the sidewall to be able to carry 20% more load than a tire with the letters LT on the sidewall. The physics of Size x PSI still holds but now the operational speed of the LT and ST are the same.
7 If there were some magic rubber that allowed a company to make tires that can carry 20% more load (the difference between LT and ST) Why wouldn't the company put that "Super" compound in their premium LT tire line?
8 Only a few tire companies make ST tires. Ever wonder why? Do you think it's possible that they do not want to make tires that they can be fairly confident will not live long enough to wear out before they fatigue? Why would you make a product where a majority of the users abuse your product? Even if you do not warranty the product for more than a year it certainly doesn't make people feel confident in your brand, does it?
If I were King I would do away with ST type tires and require a 20% load margin on LT type tires in RV trailer application and require TPMS on all RVs.
But I'm not King so all I can do is offer suggestions to help people get better tire life.
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Good post Tireman. #4 is perplexing to me. Because the TV can pull the trailer at 65, 75, 100 mph is irrelevant. Why would we expect them to slow down? To me it's obvious; what in the world would 90% of the folks towing a 10-15k trailer at 80mph do in an emergency; right here, right now, he just pulled in front of me moment? First they would mess their pants, secondly they would try some "evasive" maneuver at 80 mph with a huge load behind them that they can't control and then.....wind up splattered along the roadside...or, mess their pants, say "honey hold on" and let the trailer drive them into some unsuspecting individual causing catastrophic damage to the driver, his/her family and the other individuals.
Anyone, IMO, that is willing to drive the speed that the tires are rated for (above 65-70mph) with a trailer behind them because they can....needs to have the trailer and their license removed - you absolutely can't control it like an unloaded car/truck.
I don't get to be King either but it is fun/enlightening to share our opinions/observations/thoughts. JMO