Bird, Before I adapted 19.5 inch Alcoas to my Ram 3500, I was searching for something over load range E tires. I found some load range G in 16 inch and was happy until I personally read the fine print. They were only for use on one specific model of wheel from one specific manufacturer. The wheel was a trailer wheel. Seems the rating of the tire exceeded by a good margin the strength ratings of my stock 16 inch wheels (most others as well). These tires are made for heavy trailer service, like 5th wheel RVs.

My sis and bro-in-law have a 5th wheel RV and have had MANY tires replaced under waranty, just lots of tire problems (load range E came on it so Load range E is what he uses!)

Now, back to your story... Sounds like he did a fair job of preparation, but... I don't personally know of anyone with a good sized 5th wheel who pulls it in hills and mountains with a diesel and hasn't ended up with an exhaust brake or wished they did. I have had brake fade pretty bad on a long descent from 10,000 ft on a steep national park road with my 3500 with a large cab-over camper on it. NOT FUN! I do know how to drive, never let speed get too high on descents where braking is needed, stayed in lower gears (nearly futile on diesel) and nearly rear ended a ranger. This was the STRONG motivation to get an exhaust brake. With a good exhaust brake you use your service brakes a lot less frequently and with less vigor. I have "coasted" down steep grades out west in third gear at 55 mph using my exhaust brake that previously I took at 80-85 in same vehicle. I have DONE the Cajon pass and Grape Vine both several times with and without exhaust brake and can assure you the exhaust brake reduces the "pucker factor" by an order of magnitude. It reduces brake wear as well as fade. It keeps your service brakes cool in case you need "extra" stoppiing power.

The above comments regarding an exhaust brake are for a DIESEL powered rig. With a diesel the air intake is wide open at all times and provides little or no braking effect when you remove your foot from the throtle. (Bird, this wasn't for you but for those not experienced with diesels.)

Pat