Needing New Tires

[smoltzie]

Needing new tires & thinking of using the FMCA Discount Tire Program. Have a 40 ft class A diesel pusher. It had Michelin’s on it when I bought it & they have not served us well (two blow outs, Michelin called it “zippering”) . Have 275/80R22.5 tires now. Thinking of changing to 275/70R22.5. Looking for a better ride but with the traction, good handling in the rain etc. What tires have y’all bought with or without the program? Any info appreciated. 

[wildebill308]

I had great service with the Continental's they rode better than the Michelin did. 

I don't know what you think going to the 275/70R22.5 is going to do for you they are just shorter and the same width. I would stick with the 275/80R22.5.

Look at this tire comparator.

https://tiresize.com/comparison/

Bill

[smoltzie]

Thanks for the link. Having an existing  problem when pulling long hill that RV does not down shift until nearly at top of hill, thinking of going down to 275/70R.22.5 will improve that. Have plenty of top end to sacrifice if needed. 

[richard5933]

If you're having a problem with transmission shift points, have you had that addressed yet? If not, changing tire size is just a band-aid. Don't know how old your coach is, but it might be time for a transmission service.

If the transmission is working to specs, then the obvious answer is to use the lever and just downshift manually. Lots of people with diesel pushers, especially older ones with less HP in the engine, make a habit of taking control of things in the hills/mountains long before the transmission decides to do something. Helps keeps the engine from lugging.

One other thought that comes to mind is to confirm what size tires your coach left the factory with. Just because you got it with the 275/80R22.5 tires doesn't mean they're the correct size. Someone may have swapped out the tires long ago.

Changing tire size would be a last-ditch effort in my opinion for solving a transmission problem.

[manholt]

Agree with Richard.  What is the DOT Number on tires?  What age is coach?

[wildebill308]

11 hours ago, smoltzie said:

Thanks for the link. Having an existing  problem when pulling long hill that RV does not down shift until nearly at top of hill, thinking of going down to 275/70R.22.5 will improve that. Have plenty of top end to sacrifice if needed. 

What we have hear is not a tire problem or a transmission problem but a operator problem. The OP has never been trained to drive a big rig. Smoltzie Not picking on you. To many people get no advice or training when they buy a bigger RV. What coach do you have? 

Hearer  is the condensed version. When going up a grade and you start to loose speed manually down shift till you can maintain that speed. Watch your tack, if you get below peak torque you should down shift so you stay above peak torque outher wise you are lugging the engine. This can cause high exhaust gas temps and can cause damage. Once you find the gear that you can accelerate in hold that gear and run just below peak RPM till you crest the hill. Now you  are in the correct gear to start down the hill.

Any questions let me know.

Bill

 

[rayin]

Tire "zippering" is caused by running tires underinflated according to Michelin.

re: new tires. This time(2017) I bought 275/70R22.5 LR H Sailun truck tires. They ride well and grip the road well. Best part IMO; I bought 6, had them mounted and balanced. The total bill was $,1380 including taxes.

[smoltzie]

Good thought, will research original tire size for RV. 2004 Damon Ultrasport 40ft, 3126 CAT. Will check into Salilun.

[tireman9]

On 9/27/2021 at 10:09 PM, smoltzie said:

Needing new tires & thinking of using the FMCA Discount Tire Program. Have a 40 ft class A diesel pusher. It had Michelin’s on it when I bought it & they have not served us well (two blow outs, Michelin called it “zippering”) . Have 275/80R22.5 tires now. Thinking of changing to 275/70R22.5. Looking for a better ride but with the traction, good handling in the rain etc. What tires have y’all bought with or without the program? Any info appreciated. 

"Zippering" is the name for the failure mode when steel body tires are run with very low inflation (-20% or lower). You can get this failure on any brand Steel body tire. I suggest you get a TPMS which can warn you of air loss and with the cost of your size tires a single warning can pay for the TPMS system.

Here is a post from my RV Tire Safety blog with a picture of such a failure. There is a link to an article on Zipper failures in my post too.

 

[smoltzie]

Interesting, tires were new & inflated to spec. Michelin dealer called it zippering & Michelin ok’d replacement of two tires. Still interested in recommendations for good riding tires. 

[tireman9]

1 minute ago, smoltzie said:

Interesting, tires were new & inflated to spec. Michelin dealer called it zippering & Michelin ok’d replacement of two tires. Still interested in recommendations for good riding tires. 

Didn't your TPMS sound a warning? If not I suggest you confirm the low pressure alarm level (no lower than 5 psi below the minimum inflation needed to support the measured load on the tires.

You can fail a tire in just a few minutes of operation at extreme low inflation. BUT Just parking on a flat tire with steel body cords can "kink" the steel so that when inflated and driving down the road the "kink" is a stress riser and the "Zipper" can start.