First if tires. Looked at the DOT date and it was 2013. That's eight years and they still look great. 8R19.5 is getting harder to find, but there are metric that fit the wheels. What have been the results of doing metric?

Gary, I generally went the 7 and out but the 330i tires are approaching that age and the last few years have seen more time in the garage than on the road. Went on Contenental's site and with a few caveats suggested replacing at 10 years maximum. The trailer had a maximum number of mismatched tires when we bought it and as repairs led to investigation width and diameter were the only commonality, one was bias ply. Replaced 4, kept best one as spare. Went to check it one day and spare had blown up. At this point I wouldn't be dragging it far in summer temperatures but I think I am sidelined until fall so maybe next year. 1 to 200 mile trips probably won't see new tires.

Do your air conditioners have wall mounted or unit mounted thermostats ?

Ours are on the units and would kick off before the coach was comfortable . They blew cold air , just not long enough . I removed the interior covers and adjusted the manual thermostats . Now I can keep the bedroom 65 degrees and the front 62 degrees .
The heat index was 125 here last week . I had the front ac on and it had no problem keeping the coach at 72 degrees . That was with the coach in full sun .

Before adjusting the thermostats I could barely get it below 80 .

On the tires , I only go 7 years on the fronts and no more than 10 on the rear . I run Continental tires . Currently we are running :
Hybrid HS3 225/75/19.5 on front and Hybrid HD3 225/75/19.5 on the rear .

I have Atwood Air Command ACs. Very happy with them. Unlike the others these AC s have two fans and two fan motors.

Typical units with one motor for both fans are more noisy at low settings. Even when set at lowest speed the motor must run the outside fan enough to cool properly. The Atwood unit has two fans that run independently. That way the inside fan can run really slowly ie quiet on the low setting while the outside fans runs as needed. The Atwoods cool well. I have 15.5k heat pump version in front 13k version in back. They both work well and as said are very quiet on low. They have internal or wall thermostat choice and ducted vs nonducted plenum choice.

We are very happy with them.

Garry I have used 225R70 tires for years with good results, didn't like Bridgestone as they wore funny on the rear. Metric 225R70 fit well on 6 inch 19.5 wheels.

I recently had 6 steel wheels made so could use 245R70 19.5, they are larger in diameter (and require 7" wide wheel) and seem to wear much better. With the mileage I put on, I don't have to worry about ageing out!

Now you have me wondering , maybe mine are 225-70-19.5 . I'll look tomorrow

As for tire life.... good question. I have never seen actual scientific tire aging studies. Most mfrs suggest 7 yr maximum but they are likely to have strong motives from their lawyers and their marketing depts to push for early replacement.

There are so many variables. One would assume that the mfrs try to make sure the tire body will last as long as the tread. This obviously can be done as retreads are commonly used, sometimes more than once.

One thing for sure overloading/overheating will quickly destroy any tire regardless of age. Tread separations or sidewall ruptures are the result.

Aside from road hazard damage which is unrelated to the tires age, heat is the number one enemy.

The flexible “rubber” compounds are the weak link. Cords and belt fibers are quite durable. As long as the rubber remains flexible the tire will hold air and roll smoothly. The rubber has “plasticizers” which help keep it flexible. These are what make tires smell like tires. Regular flexing of the rubber keeps these materials dispersed in the rubber compunds.

Heating the rubber drives the plasticizer out of the rubber. UV light does the same thing at the surface. Result is stiffer tire and surface cracks begin. Ozone from the air oxidizes rubber with the same surface result. When the cracks get deep enough water can enter and cause damage to cords and belts.

So, getting to the point, tire life will vary greatly. Assuming no road hazard damage the life depends on the condition of the rubber compounds.

Proper inflation, proper loading, regular use and avoiding heat, sun and ozone promote tire life.

So low pressures, poor storage and heat will kill them quicker.

So, if you drive them regularly, well inflated, keep them covered and away from heat and pollution you may be the 10 yr guy.

If you live in Florida, drive infrequently, let them get low on air sitting in the sun you are more likely the 7 yr guy.

Driving safety issues aside, another thing to consider is collateral damage from the tire failure. Tread separation can cause remarkable damage $$$ to the tirewells. My farm buddies run the tires almost till they blow on their farm wagons because they are exposed and do no damage. In an RV tirewell is another story! (Those are the guys I give my tires when they age out)

I have heat here in Yuma, but tires do not get any hotter sitting than driving and I keep them covered. I use oriental tires as I have been told that they still us natural rubber which doesn't weather check as fast. I have found no documentation to support this.

As to AC I have decided on Furrion. Doing 15.5K. Dual motor like Atwood at half the cost. Also has the lowest DB rating I can find. Atwood in very close but Dometic seems to be discontinuing Atwood.

When we first we got ours it had 25yr. old original tires. I replaced with Goodyear that were to have additive to keep longer. I keeping proper air and keeping out of sun is the best you can. I have only had 1 blow out in my life and that tire was to old. If you are keeping the coach I would change out 8-10 years for peace of mind.



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