The topic of Class B RV tire pressure comes up quite a bit. Tires all look like black rubber donuts, and we look at the tread, the advertising copy, and perhaps read some reviews and talk to friends when selecting a tire. Sometimes we let the tire guy tell us what we need.
As Class B owners, we need to go a little deeper. Our vans weigh in at about 5 tons, give or take. That's a bit more than a ton per tire, and that translates to a lot of load on a black rubber donut. Not all rubber donuts are made the same, and not all rubber donuts are suitable for our Roadtreks.
The first stop when selecting the tire is the driver's side door. Open the door, look at the pillar, and find the label that tells you the appropriate tire information. Don't let anyone tell you that you need something different, or that you should use a lower tire pressure for a better ride. Remember all those Ford SUVs that rolled on the highway? That was due to low tire pressure.
Most of us on the heavy duty chasses will be looking for Load Range E tires. Load range E tires are truck tires, they are not “extended range” passenger tires. Those may be sometimes used on 1/2 ton chassis. Roadtrek builds everything on either 3/4 ton or 1 ton chassis, and all of those need Load Range E tires.
Sometimes you may also see tires rated as a Load Index; the Load Index is a number with light duty tires having a load index in the 80s and heavier duty tires having a load index of over 100. You can get yourself very confused by going between Load Index and Load Range; keep in mind that Load Index is typically used for passenger tires, and you need truck tires, so you need a tire with a Load Range E.
Some of the older Roadtreks used “Extended Range” passenger tires. When in doubt, check the sticker on the driver's side door. If that's not clear or the sticker is missing, you can usually find out by checking any of the tire websites, or with the chassis manuracturer, or Roadtrek.
http://www.tirerack.com is my favorite; you put in your model year and vehicle type and they provide the correct tire sizing. Keep in mind when using these websites that your Roadtrek model is typically one model year newer than the chassis; my 2001 Chevy Roadtrek, for example, is built on a 2000 Chevy G35 chassis.
If bought your Roadtrek used, and you're not sure of the tires, both US and Canadian law requires that every tire is imprinted with extensive information about the tire itself. Once again, TireRack has a great explanation:
Sometimes you might hear people tell you that if you upgrade to a certain kind of tire, you can carry more load. Load carrying capacity is a function of tires, rims, brakes, bearings, axles, chasssis, frame, and ….. It's determined by the manufacturer. Nothing you can do as an owner will add to the load carrying capacity of your vehicle.
If you use heavier rated tires than you need, you will end up with less money in your pocket since they're more expensive, a harsher ride due to the heavier duty construction of the tires, and quite possibly worse gas mileage. Go with the tires the manufacturer recommends, and stay within your load rating.
Lastly, many people recommend that you replace your tires every 5 years. Firestone recommends a 7 year interval, and will not service tires older than that. With the relatively low mileage most RV tires see, it's likely that our tires will age out before they wear out, so keep an eye on the date of manufacture and the calendar, and schedule that expense accordingly. Tires, like oil changes, are a maintenance item, especially with big, loaded, and expensive vehicles like our Roadtreks. Chances are, with Roadtreks lasting more than 20 years, we will do 2-4 tire changes in the life of our Roadtrek.