Class C tire problems

[aa0ri]

Lots of good advice as usual but one thing that hasn't been mentioned is wheel capacity rating. Wheels as well as tires and suspensions are rated for that vehicle. If you put on a heavier rated tire and don't check the rating for wheels and axles you could be in for some real trouble if you exceed that weight rating, tires are just one part of the equasion. Up sizing your tire rating is fine if you don't exceed any of the other ratings involved. Remember the heavier rated tire weighs more too.

[Judge]

Originally Posted by aa0ri

Lots of good advice as usual but one thing that hasn't been mentioned is wheel capacity rating. Wheels as well as tires and suspensions are rated for that vehicle. If you put on a heavier rated tire and don't check the rating for wheels and axles you could be in for some real trouble if you exceed that weight rating, tires are just one part of the equasion. Up sizing your tire rating is fine if you don't exceed any of the other ratings involved. Remember the heavier rated tire weighs more too.

That is a fair point....

If you look up the actual weight ratings of the individual components like the axle, you typically find they are rated higher than the GVWR of the vehicle. Many times the GVWR is tied more to the actual tires installed during manufacturing than anything else.

As I have said all along everyone needs to do their own homework.... but I think it is fair to say going with the C-rated tire of the same size won't put these Class C's over the breaking point and the safety advantages outweigh any downside.

[Chance]

A significant number of larger (longer wheelbase) Class C tire failures seems to come from outside passenger-side rear tire. While load and pressure may play a part, I would bet that driving onto or off curves also plays a part. That’s got to stress tires significantly.

Not calling anyone out, and will admit on doing it a few times myself on longer rental motorhomes when making a sharp right turn into or out of a parking lot. Turning radius on stretched E-Series can get pretty long.

[Leslie Meyer]

There’s a whole lot to digest on this thread so I have a bit to add! Are the front rims not different from the rear tandems? If the are which spare would you carry?

[16ACE27]

Originally Posted by Leslie Meyer

There’s a whole lot to digest on this thread so I have a bit to add! Are the front rims not different from the rear tandems? If the are which spare would you carry?

The rims are all the same.

[Bob Denman]

Leslie,
That's a good question. ::
If they are different: I'd carry a rear tire.
It'll fit on the rear (obviously. ), and has at least a fair chance of fitting the front.

[The_Breeze]

Originally Posted by Judge

The chassis is a big part of that cost increase:

- Diesel Power
- HD Transmission
- Heavy Duty Axles, Brakes and Suspension
- 19.5" or larger commercial truck rated tires

Unless it has a Cummings 6 and Allison tranny, it may not be worth twice the money?

[The_Breeze]

Originally Posted by jadatis

The influence of water is also exagerated often.
Even if you put a gallon of liquid water in a tire, at 212 degr F ( boiling point at ambient pressure of 14.7 psi) , the extra pressure for the waterpart is max 14,7 psi.
OK, thats a lot on 65 psi, but it then gives lesser deflection,so lesser heatproduction then dry air, wich is positive for the temp of rubber of tire.

And for 162 degrF in tire only 5 psi extra rising of pressure by the water.

Filling tires with a compessor with vessel, then first give vessel highest pressure it is allowed, then fill the tires to needed pressure.
The watergas then condenses to liquid, wich you can drain, or uf not, wont go in the tire, and tou have less then 1% water as gas in the tire. And this is only if you dont want the pressure rising by water.

Why you hear about nitrogen in the tires. Especially OTR rigs,

[Bob Denman]

I use "nitrogen light": it's only about 78% pure ...

[jadatis]

Originally Posted by The_Breeze

Why you hear about nitrogen in the tires. Especially OTR rigs,

I once read that they started filling Nitrogen, when they started filling on location, and Nitrogen was cheapest in cilinders available, because waste product of Amoniac production .

Commerce made it a selling argument.

[Judge]

Using Nitrogen in tires does make a difference....

The tires on my GMC Canyon needed replaced and they used compressed air. I had them replaced at Costco (hard to beat Costco for tires), which uses Nitrogen.

With the old tires I could see a 3 to 4 PSI difference when the daily temp swings would go from mid-30's in the morning to near 70 during the afternoon.

With the new tires I now only see about a 1 PSI swing with similar temperature swings.

[lwmcguir]

I ran nitrogen in my second set of 16 ply tires on my F550 crew cab pickup

70k on the first set and gave the truck to little brother with second set still on the ground

No measurable difference than with the air in the first set monitoring temperature with similar loads

Both sets were inflated to 115 psig steering and duals

If nitrogen is free I use it, otherwise shop air compressor

A few tire shops include nitrogen an option

[jadatis]

Originally Posted by Judge

Using Nitrogen in tires does make a difference....

The tires on my GMC Canyon needed replaced and they used compressed air. I had them replaced at Costco (hard to beat Costco for tires), which uses Nitrogen.

With the old tires I could see a 3 to 4 PSI difference when the daily temp swings would go from mid-30's in the morning to near 70 during the afternoon.

With the new tires I now only see about a 1 PSI swing with similar temperature swings.

If 35 psi at 35 degrF goes to 68 degrF, it will go to 38.3 psi with completely dry gascompound.
So your Nitrogen filled tires can never only rise to 36 psi in those conditions.
Mayby together with that, you chanched TMPS- system to one that calculates back to 65 degr F.
Some motor tmps have that standard.

[Judge]

Originally Posted by jadatis

If 35 psi at 35 degrF goes to 68 degrF, it will go to 38.3 psi with completely dry gascompound.
So your Nitrogen filled tires can never only rise to 36 psi in those conditions.
Mayby together with that, you chanched TMPS- system to one that calculates back to 65 degr F.
Some motor tmps have that standard.

The TPMS is stock GM. The only thing Costco did was change the seals for the stock sensors.

[Big-Foot]

Understanding that the OP had no choice but to mix and match -

I used to hang out with tire engineers back when I was sponsored by BF Goodrich and they all concluded the very same thing when it comes to dually tires:
1) They must be rated as a dual tire
2) They must be made by the same manufacturer and be the same size/tread pattern - preferably from the same lot.
3) They must be inflated to exactly the same cold pressure

Originally Posted by The_Breeze

Why can't some 225/75R16's be used in a dually configuration?

Same engineers that I quoted from above said that tires need to have sufficient air-space for cooling while running at full load capacity. Dual rated tires can run at a higher operating temperature...

[Bob Denman]

Big-Foot,
Thanks for the background info from the experts.

[The_Breeze]

Originally Posted by Bob Denman

Big-Foot,
Thanks for the background info from the experts.

No kidding - right. Ditto. Thank you!

[Judge]

That is all good information from the experts......

There is one piece of information I still think is important to consider for these Class C's (and even some small Class A's) and that is that standard LT-type tires sold as part of a cutaway chassis are designed for light truck applications i.e. pick-up trucks, SUV's, vans, etc. Ford, Chevy, etc. have no idea what application the buyer will use the chassis for so it is setup with basic tires and a suspension that can handle the max GVWR during production.

The RV manufacturers should either order the chassis with upgraded C-type tires instead of the LT tires or they should install them during coach manufacturing. That's just my opinion if you want to look at it as a pure safety play.

While an LT tire does have a higher weight rating than a typical passenger vehicle tire and they can be rated for dual tire application, on many Class C's the tire is running near it's max weight rating all the time if you have a coach that weighs over 13,000lbs before you load it with gear. Once a coach is loaded with gear, you are up against the limits of an LT tire.

Assuming the OP has been diligent about monitoring air pressure, etc. three blowouts certainly lends itself to a weight issue.

[lwmcguire]

Judge is Absolutely right on
LT tires do not belong on a motor home

A 10-20% safety factor on tire loading isn't going to happen with 10 ply LT tires on very many loaded RV's

Originally Posted by Judge

That is all good information from the experts......

There is one piece of information I still think is important to consider for these Class C's (and even some small Class A's) and that is that standard LT-type tires sold as part of a cutaway chassis are designed for light truck applications i.e. pick-up trucks, SUV's, vans, etc. Ford, Chevy, etc. have no idea what application the buyer will use the chassis for so it is setup with basic tires and a suspension that can handle the max GVWR during production.

The RV manufacturers should either order the chassis with upgraded C-type tires instead of the LT tires or they should install them during coach manufacturing. That's just my opinion if you want to look at it as a pure safety play.

While an LT tire does have a higher weight rating than a typical passenger vehicle tire and they can be rated for dual tire application, on many Class C's the tire is running near it's max weight rating all the time if you have a coach that weighs over 13,000lbs before you load it with gear. Once a coach is loaded with gear, you are up against the limits of an LT tire.

Assuming the OP has been diligent about monitoring air pressure, etc. three blowouts certainly lends itself to a weight issue.

[The_Breeze]

Originally Posted by Judge

That is all good information from the experts......

There is one piece of information I still think is important to consider for these Class C's (and even some small Class A's) and that is that standard LT-type tires sold as part of a cutaway chassis are designed for light truck applications i.e. pick-up trucks, SUV's, vans, etc. Ford, Chevy, etc. have no idea what application the buyer will use the chassis for so it is setup with basic tires and a suspension that can handle the max GVWR during production.

The RV manufacturers should either order the chassis with upgraded C-type tires instead of the LT tires or they should install them during coach manufacturing. That's just my opinion if you want to look at it as a pure safety play.

While an LT tire does have a higher weight rating than a typical passenger vehicle tire and they can be rated for dual tire application, on many Class C's the tire is running near it's max weight rating all the time if you have a coach that weighs over 13,000lbs before you load it with gear. Once a coach is loaded with gear, you are up against the limits of an LT tire.

Assuming the OP has been diligent about monitoring air pressure, etc. three blowouts certainly lends itself to a weight issue.

Absolutely. The way some of these longer C's are loaded up, I'm surprised they last as long as they do sometimes.