As Greg points out the "floating" tires are very susceptible to irregular wear patterns. Some tires are made specifically for these axles and some are made specifically for drive axles. I do not know the dynamics that creates that situation.

On the coaches that used 365 tires on the steers and tags, and 315 on the drive tire care is more critical than ever. When I had a tire wear issue I could simply place the tire in question on the drive axle and that unusual wear pattern was corrected over a period of time. Because of the steel inner wheels on 45 foot coaches or because of a wheel polishing issue doing that involves breaking down the tires and wheels, but at least you could salvage a very expensive tire when its wear was caught promptly. That option is not available on coaches with dissimilar tires so checking pressures and feeling for any wear problems becomes critical.

With the price of 315 tires now north of $600, I think a tire monitoring system that works should almost be standard equipment on the shells. I also think it should be the band type so there is no added potential for leaks, and I also think the battery life in the sensor should be five years to parallel the life of the tire. As long as I am bloviating I also think the sensors should display actual tire pressure and not just a low pressure warning.