Matching Tire and Wheel Capacities (follow up)

[Community Alumni]

The short of my question... Can I have a tire/wheel combination where the load capacity of the tire exceeds the load capacity of the wheel?

Now the long version... I currently have the usual 14x5.5 steel wheels stamped for 1870 lbs. My current tires are ST205/75R14, Load Range C, 1760 lbs, 50 psi, 65 mph. The weight of my trailer is well within these capacities. I'm not worried about that at all. Nevertheless, the tires are old and wearing thin. I'm interested in upgrading to Load Range D. Load Range D specs are more like 2100 lbs, 65 psi and 80 mph. What really interests me is the higher speed rating. Not that I plan to go 80 mph, but I like that margin of error. That is, I'd rather go 60-65 mph on 80 mph tires versus going 60-65 mph on 65 mph tires. That's my motivation. So then... Can I put the Load Range D tires on my old wheels? I though I once read something about not exceeding the psi rating of the wheel (which in turn dictates the tire selection), but I see no psi information on the wheel.

Thanks!

[MFL]

JIMNLIN wrote:
Wise choice.
Now to protect your new tires warranty from Carlisle keep them pumped to the max sidewall pressure.......on the road even and especially when stored for the winter.

Good point, on the Winter storage being at max sidewall pressure! I'm sure many overlook this issue, and tire pressure can drop 10 lbs or more in extreme cold. It is especially hard on tires to be under inflated, and standing for many months.

Jerry

[JIMNLIN]

Wise choice.
Now to protect your new tires warranty from Carlisle keep them pumped to the max sidewall pressure.......on the road even and especially when stored for the winter.

[Community Alumni]

Thanks again for all the replies and advice. I selected Carlisle Radial Trail HD LRC tires. These have all the same specs as my old LRC tires so I know they're compatible with my old wheels. The difference is that they're rated for 81 mph instead of the usual 65 mph. So now all the tire specs well exceed anything I ever plan to do with the RV. We'll see...

The larger lesson is that I should have done all this last year. My old tires were seven years old and well used. Two of the four had tread deformations from something coming apart inside. I think I dodged a bullet.

[gmw_photos]

If you run a Sendel brand wheel ( a popular and common wheel in the towable market ) all of their 14" rims are rated for at least 65 psi. Once you get into their 15" and larger they are all rated for at least 80 psi.

My travel trailer came with this brand, and LR C tires. When I switched to LR D I began inflating to 65 psi.

[Huntindog]

Yes, moving up to a D rating will be an increase in reliability. And not just at higher speeds.

I had a C tire get a rock puncture on a gravel forest service road at 2-3 MPH! I heard it when it happened as the widows were down. What a pain. Almost at the campsite, and had to change the tire on the road.
While I cannot say for certain that a D tire would have fared better, with it's more robust construction, it probably would have. I was done with Cs after that, and have never had that happen again.

As for the rim PSI. I simply ran the tires at the max the rim was rated for. It worked well, and gave me some of the benefits of the higher rated tire.

As for the ride being rougher... It makes sense that it should be. But it is not a discernable difference in my experience. That TT I had the rock puncture on started life on Cs and when I sold it had Es.(80PSI on new rims) Not a difference in ride that I could tell.

What will improve the ride greatly if that is a concern is installing one of the shock absorbing equalizers on the market, Trail air Equaflex etc. Those flat out work and make a huge difference.

[Atlee]

My new trailer, Jayco 23RB, came with OEM ST205/75R15 LRD Goodyear Endurance tires. Both the tire sidewall and the yellow sticker on the trailer says 65 psi, so I air them up to 65 psi.

I do not derate my tires by putting less air in them.

[rbpru]

It all comes down to, what is your objective and how much are you willing to pay.

I add 3 years and over 15,000 miles to a used TT before I replaced the 7 year old China bombs. I kept them for farm trailer use as they still have a lot of tread but they were 7 years old and we do a lot of travel.

I replaced them with D rated tires because they were only $20.00 a tire more.

Weight wise, my loaded for the road 25 ft. TT crosses the scales with 5700 lbs. on the 7000 lb. rated axles and 700 lbs. of tongue weight.

Since my new tires are C rated at 55 psi and D rated at 65 psi. I run them at 60 psi. This gives me a bit of leeway on the tire pressure.

From past experience 65 psi transfers a lot of shock to the TT.

Speaking from experience, a rim bending road hazard will wipe out any tire, regardless of its load rating.

[JIMNLIN]

mike-s wrote:

JIMNLIN wrote:
It make no cents/sense to use 50 psi in a 65 psi rated tire in a trailer position...JMO.

It absolutely does. The tires are part of the suspension, and more pressure makes for a rougher ride to vibrate your trailer apart. Wheels may have pressure limits. There's a reason the load/pressure tables have numbers in between the max for each load range. A LRD tire at 50 psi is already going to be slightly stiffer than a LRC at 50 psi, just due to the additional belt/ply strength. Although most ST tires get replaced before the tread wears out, even treadwear is another consideration.

Carlisle has a minimum pressure chart but recommends max sidewall pressure per their tire warranty.
Most folks know when we derate a 65 psi tire to 50 psi on a trailer it will run hotter than at 65 PSI. BTDT.
The benefit of the D tire is lost.
You can abuse your tires on your trailer by derating them. Its your money.

[time2roll]

Good excuse to get some snazzy aluminum wheels rated for the D-65 tire.

aluminum 14x5.5 rated 2040 same as GYE LRD $68

[SoundGuy]

prichardson wrote:
Both the new Goodyear Endurance and the new Carisle HD series ST tires are listed as having 80 MPH ratings at standard pressures.

Not sure that's entirely correct - in an ST205/75 R14 size the Goodyear Endurance is available in just LR D but the Carlisle HD in that same size is available in both LR C and LR D.

FWIW, my own set of Goodyear Endurance ST205/75 R14 tires do say on the sidewall "For maximum load inflate to 65 p.s.i." ... I did and I have to say the trailer tows FAR better than it ever did with the previous off shore, soft sidewall LR C tires that were supplied with the trailer. I tow at the posted highway limit which here in Ontario tops out at 100 kph so I'd rarely see any more than 110 kph. These tires are mounted on the original mag wheels, are cold inflated to 65 p.s.i. and I have no plans to run them any lower. The ride is anything but harsh as some keyboard pundits are theorizing without the benefit of having actually run these tires themselves. :R

[mike-s]

JIMNLIN wrote:
It make no cents/sense to use 50 psi in a 65 psi rated tire in a trailer position...JMO.

It absolutely does. The tires are part of the suspension, and more pressure makes for a rougher ride to vibrate your trailer apart. Wheels may have pressure limits. There's a reason the load/pressure tables have numbers in between the max for each load range. A LRD tire at 50 psi is already going to be slightly stiffer than a LRC at 50 psi, just due to the additional belt/ply strength. Although most ST tires get replaced before the tread wears out, even treadwear is another consideration.

[JIMNLIN]

From what some Goodyear Endurance load D owners have said the tires sidewall says to "inflate to 65 psi"...which indicates Goodyear like Carlisle and other ST tire makers wants their tires to be used at max psi for max reliability and max performance.

Its been my experience wheels can crack or split the wheel bead seat when over pressured when carrying weight. BTDT in my younger and dumber days when I first got into the hauling business.....even after my trailer dealer warned me not to over inflate a wheel or tire above their recommendation.
As mentioned wheels have a max psi and load capacity. If your don't then find out from their mfg or importer what it is.
Goodyear also says:

Goodyear Tire and Rubber .... weighing RVs
Special Considerations

Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up.

Many older 14" trailer wheels centers and rims were made from thinner material and had a 50 psi max rating. Most newer wheels have thicker or are a higher tensile strength and can carry a 65 psi. Let the wheels load/pressure ratings determine the tires load range (psi). It make no cents/sense to use 50 psi in a 65 psi rated tire in a trailer position...JMO.

[rbpru]

As mentioned, you can put semi tires on your TT but you do not change the axle rating.

Most people perceive a load range D being stronger than a C rated or a E stronger than a D. They will carry more weight but they do not ride as smooth, resist road hazards or provide a magic cure for everyday tire issues.

Changing to D rated tires does give a measure of protection, as it allows the loss of tire pressure while still maintaining weight rating. My D rated tires at 65 psi still carry a C rating a 55 psi.

Also, upgrading to a D rating is like chicken soup, it cannot hurt and feeds our bigger is better psyche.

[prichardson]

Both the new Goodyear Endurance and the new Carisle HD series ST tires are listed as having 80 MPH ratings at standard pressures.