[lunge motorsport]

Upgrading tire size, here’s my take…


RV tires, wheels, brakes and suspensions are the bare minimum that the manufacturer can legally install to accommodate the load, in most cases. The sizing specified for that particular coach should, in my mind, be considered a minimum rating. Some of the higher end manufacturers will provide higher quality components but that is not the standard in this industry. Citing a section of a manual prepared by the legal team of a manufacturer that states that replacement tires and wheels should be the same as OEM is narrow minded and not in the best interest of performance or reliability, rather it is in some other interest that I don’t understand.Your tow vehicle has the same verbiage in the owner’s manual as well but there is an entire worldwide industry devoted to upgrading wheels and tires on just about every piece of equipment that rolls. The notion that end user upgrades are not allowable is ludicrous.


In my opinion, the biggest wheel width and diameter that will bolt on your coach safely, providing it meets the minimum weight requirement and matches the “tire” manufacturers recommendations, is a performance upgrade. There are of course, many considerations in that equation. Ride height and clearance are just two of the major factors. Larger tires on the same width wheel is a spec that, while I’m not generally a fan of due to increased sidewall flex, if it provides a load bearing margin of safety, I could see that as an upgrade. BTW, I made that same upgrade many years ago on a 26’ Aljo and was pleased with the margin of safety it provided.


My coach was provided with 15x6’’ upgraded aluminum wheels with 225/75 15 D rated Trailer King tires, the coach GVW is 10,300 lbs. Sure it meets the minimum standard but the term inadequate comes to my mind. I know that trailer wheels and tires do not have the same demands as steer and drive wheels on a tow vehicle but come on now, my 86’ 2500 lb Jetta had 6’’ wide wheels…stock!


My coach now has 17x9’’ wheels with 245/75 17 e rated tires that spec at around 600 lbs greater capacity, each. Some of the “by the book guys” may say that trailer tires have greater side loading built in to their carcass, but my 17’’ e rated LT tire has a much stiffer sidewall than the 15’’ ST tire that was spec’d for the coach.
Now about valve stems…A quick check on the Tire Rack website produced some pretty good info on valve stems. It seems that all rubber valve stems used today have a minimum rating of 65 psi, so I don’t see it as a negative if your choice is to up your tire to a D range tire, you will buy new stems on the new tire mount up I presume.


Wheel rating…Can’t imagine that any steel or aluminum wheel would not meet a 65 psi rating but that number should be stamped on the inside of the wheel. As you did not indicate that you intend to carry more weight and that you are interested in the safety factor that a higher rated tire will provide, a load range D tire in a 225/75 15 ST tire is available and also spec’d for a 6-7’’ wide wheel, I see them on the Tire Rack website with a rating of 2540 lb. This was not a recommendation for that specific tire, just an example of availability.


My opinion is that I would make that change without hesitation, but would consider a rim upgrade to a wider width, if it would fit.


Cheers