I've got an '82 class C motorhome on an E-350 dually chassis, running 8.75R16.5 tires (load range D). I just had my driver's outside rear tire blow out violently last weekend. It was my spare tire (no idea of age, at least 10 years old, but lots of tread, always under a tire cover). Both the spare and the 6 running tires are load range D, but all I can find locally is a Firestone Transforce, Load range E. The 16.5" tires are getting rare according to the tire shops.

I had the driver's side outside dually tire blow out in 2006 too, so I'm wondering - should I run the E range tire in that location, or make it the spare tire? Will it distribute the load equally if I run the same air pressure as the other dually tire next to it? If I had two tires blow on the driver's outside dually and nowhere else, is this due to the nature of the vehicle's loading?

I replaced all the tires in 2006, and have less than 10,000 miles on all of them. I run 60 psi in all 6 tires, and the only reason I had the spare on was that the driver's outside dually tire had gone flat and broke the bead. The shop said it was a tiny bead leak, but I'm thinking it might have been the valve stem extender I had on there. I don't think I ran the rig with the tire flat, but if I did, I'm not sure I trust the tire anymore. I'd like to make this tire my spare, and see if it holds air for a few months.

 

Personally, I wouldn't mix n match tires on any axle, and certainly would advise mixing them on a single location at the rear of a dually. On the rear of a dually, you don't even want to put identical tires with different tread depth on the same hub, or it can lead to uneven tire loading.

Tires that are over 8 years old, even if they have never been mounted on a wheel or had air in them, are a danger. The compound will deteriate over time, and 8 years is about the max "safe" life of the tire, from it's manufacture date. Motorhomes and trailers that aren't used enough to wear tires out before they "expire", are prone to having sudden tire failure, without warning.
Tires should be replaced after they reach 8 years from date of manufacture, regardless of tread depth.

 

It's odd that that same tire blew out and none of the others, is that side facing the sun when it's parked, or see more chlorinated water?

 

It's the side that the neighbor's sprinkler system hits all summer, but the sun exposure is about the same.

 

Tire covers/shields might be a worthwhile investment, if you can't park it in a different spot.

 

I personally don't run anything less than load E anyway, so I would put all of them as such. I quit running 16.5 rims because of availability, but I had the opposite, all I could find were load D, which won't hold up to my trailer loads.

 

I think we're straying from the original question. I'm not buying 6 new tires, nor am I buying 6 new tires AND rims. One new tire is almost $200.

I have two choices - run a brand new load E tire next to the existing load D on the same hub; OR put the new load E tire on the rear bumper and run the load D tire that lost air somewhere in the last month.

 

How many miles do you typically run it? I know my sister mixes and matches tread patterns, depths and such with no issues on the bearings and such. I would be sure to keep the air pressure about the same even though the load E will run higher pressures than the D can. If you air it to it's max, it will be stiffer and such than the D will be.

 

Option C. Put the load E tire (and a mate) on the front, one of the old D tires on the back bumper, and the other in storage location, just in case.
Yes, this will cause you buy another tire. But, you'll have new tires on the steering axle, and the older tires will be on the rear, where they have a running to help keep you in control, should another let go without warning. Given that a couple have already failed, I'd seriously rethink running these on the steering axle. Blow a steer tire, and you become a useless passenger that just happens to have a steering wheel in your hands, at least for a few seconds. That's all it takes for disaster to strike........

 

I had a inside tire on my Chevy Class C blow out, they were D load ranges, the only replacement available were E's..........the inside tire on the other side looked suspect also so I replaced it as well with the same type E. According to the tire dealer, in this case, only run the E's in the same position (insides or out sides) accordingly........so far, so good, not thrilled about the combo but, I do not have $1,300 for 6 new 8.75x16.5s load range E's laying around!

 

Option C is sounding pretty reasonable.

 

I had the motorhome weighed this morning
Front end 3500 lb
back end 7000 lb
total vehicle weight 10500 lbs

I figure this puts about 1975 lbs per rear tire and 1850 lbs per front tire (adding on 1100 lbs for people and camping equipment). That's no where near the load limit of 2550 lbs for the class D tires. If one of the dualies goes flat, that throws 3950 lbs on the other tire, which is greater than the load range E limit of 3550 lbs.

Just mulling over this new information. At least the current tires aren't overloaded.