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!

[mike-s]

Not sure where you get the "Load Rang D specs are more like ... 80 mph." By the way you said it, you seem to think any LRD is rated for 80 mph, and that's not true. Although there may be some specific tires which are rated for 80 mph, ST tires only need to handle 65 mph when using the normal load/inflation specs, and that's all many are rated for.

For all ST tires, you are allowed to go to 75 mph by increasing the pressure by 10 psi over that given in the tables (not to exceed the max pressure), and to 85 mph by both increasing the pressure by 10 psi and derating the load limit by 10%.

[Community Alumni]

Okay, thanks for the all replies! I found this chart...

http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

So it looks like I could buy the Load Range D, inflate them to 50 psi and I'd be right where I am now except I'd have a tire better than Load Range C.

[WolverineState]

"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."

That's was my motivation also...I just did the exact change you're thinking of back in August by upgrading to Goodyear Endurance. I inflate them to 60psi instead of the 65psi and I won't travel over 65mph. With two trips completed since then, there's been no issue. I also added a TPMS for my peace of mind.

[mike-s]

CapriRacer wrote:
It is my understanding the wheels fail due to overload, not overinflation. Since the wheels will be carrying the same load, there isn't a problem with using tires that uses more inflation pressure.

Wheels also have max pressure ratings. For example, Dexstar 017-324-xx wheels are rated for a max of 1870 lbs and 50 psi.

And, when going over 65 psi, high pressure valve stems are required.

[bobndot]

The wheel also has a psi rating. Probably 50#.
I asked the same question at various tire shops including popular on line shops and received the same answer.
"Putting a D tire @ 65# will not harm the steel or aluminum OEM wheel rated at 50#."

Im not saying its right or wrong to do it, it's just the common answer i received.
Moving up a step in tire size is not that much of a price difference therefore i can't see them saying it to make more money.

On your trailer, are the wheels hub or lug centric ? Hub is stronger to support the weight on the axle hub, i have seen lug centric wheels crack n split when overloaded while snapping off the lugs. It occurs when after market wheels are installed on vehicles and then overloaded.

how to tell if a wheel is hub centric or lug centric

Personally i feel comfortable enough to increase the tire size and have been doing it for many years. Im running 4 different trailers on the road covering a lot of miles and have had no issues. All my wheels are hub centric and slightly over the psi but not over the load rating. I have never seen a visible crack in any wheel.
You dont have to run the new tires at 65#, run them at 55 or 60. They will decrease the load a bit but you are already within your gross specs so its not a problem in your case or mine.

[mike-s]

SoundGuy wrote:

mike-s wrote:
A ST205/75R14, LRD is rated for 1855@55, which closely matches your wheels.

My understanding is an ST205/75 R14 LR D tire would require a cold inflation of 65 p.s.i., not 55 p.s.i. Indeed, the new Goodyear Endurance in this size is a LR D tire rated for 2040 lbs @ 65 p.s.i.

Your understanding is incorrect. You're quoting the max load/inflation for an LRD. Running at max pressure is not required, nor is it even advisable when not required for load or speed purposes.

And, _all_ tires of that size share the same load/inflation table. The tables are standardized within the industry.

[CapriRacer]

It is my understanding the wheels fail due to overload, not overinflation. Since the wheels will be carrying the same load, there isn't a problem with using tires that uses more inflation pressure.

[moresmoke]

The load range D tire is capable of handling increased pressure, but you are not required to inflate it to that pressure. Install the LR D tires and inflate them to the same 50 psi. The load capacity will be the same as the LR C at 50 psi.

[SoundGuy]

mike-s wrote:
A ST205/75R14, LRD is rated for 1855@55, which closely matches your wheels.

My understanding is an ST205/75 R14 LR D tire would require a cold inflation of 65 p.s.i., not 55 p.s.i. Indeed, the new Goodyear Endurance in this size is a LR D tire rated for 2040 lbs @ 65 p.s.i.

[mike-s]

Range, not rang.

You can put a higher capacity tire on a wheel, but the combined rating is the lesser of the two.

A ST205/75R14, LRD is rated for 1855@55, which closely matches your wheels.