tires overloaded?

[aruba5er]

recently bought a new TC and fully loaded, ready for travel, weighed it at a CAT scale. left me just a few #'s under what the tires are rated for. It rides good, no sway, no sag but being so close to max on the rear tires bothers me. last thing I need to do is blow a tire. Is this thing that bothers me worth looking into larger tires, wheels? As is, tires are new Michlean's and capable of 50/70 #'s more.
Thanks for your opinions.

[Marcela]

Why do OEM rate capacity at 80% of tire rating?

[JimK-NY]

Since this is a truck camper and RV forum it is worth mentioning the issue with many 1/2 ton trucks and SUVs. They are basically passenger type vehicles which are not meant for continuous service at full load. P tires are NOT load rated for continuous use at full load. LT tires are designed, built and rated differently with the intent that they can be used for full time work.

[Grit_dog]

I'll qualify with this is not a recommendation, but rather a personal experience. (And it's one that thousands or more test every day based on the trucks you see rolling down the road to work everyday.)

The bulk of the 30 or more company trucks I've had over almost 25 years have been 1/2 tons and every one of those work trucks came with the normal cheap, small, P rated tires.
Most of those trucks got worked hard. Up to 3 tool boxes or a big cross box and a 80gal slip tank and that was just the everyday 24/7 loads. Now add in additional load in the bed and/or pulling trailers with significant tongue weight at the same time. Most of those 1/2 tons got a set of add a leafs or timbrens or something to help the perpetually squatted and frequently "overloaded" stock rear suspension.
Probably average 20k miles out of most OE 1/2 ton tires. And being company trucks, I couldn't justify the cost of new heavy duty tires on a new truck. My recourse was and is, pump up 44psi rated rear tires to 50-60psi when needed and move on. So far so good and I average about 30k miles a year on company rigs.
Throughout that experience, I've yet to lose a tire while over loaded.
Based on that experience along with seeing many more overloaded situations that would make my experiences look like I was a rookie at overloading, I do not take exception to loading a tire or rim to it's max rating.
That said, I see the value in over engineering some things a bit and do so when I can.
Food for thought....

[CapriRacer]

JimK-NY wrote:
The Ford/Firestone "thing" was not an issue of load ratings. There were defects in the manufacturing. Most of the issue involved manufacturing in Venezuela where failure rates were 1000x the failure rate for Dayton manufacturing.

Don't you mean Decatur? (Illinois). I was talking about what happened around August of 2000, and nothing involved Venezuela.

Here's my analysis: Barry's Tire Tech: The Ford / Firestone Controversy

[JimK-NY]

The Ford/Firestone "thing" was not an issue of load ratings. There were defects in the manufacturing. Most of the issue involved manufacturing in Venezuela where failure rates were 1000x the failure rate for Dayton manufacturing.

[billtex]

JimK-NY wrote:

Ski Pro 3 wrote:
Running close to max on the tires is risky. It leaves you almost no room for emergencies such as a pot hole, something falls off the vehicle in front of you, even an emergency evasive maneuver could cause a tire to roll off the rim if it's at it's rated or close to.

Leave yourself some margin between rated and actual loads on your tires. 10% maybe.

Again, LT tires are rated for continuous use at full load. A safety margin is built into the load ratings.

If you want some extra "margin" of safety, why pick 10%? Why not get a significant margin, say 50%? Also where did you come up with the warning on tires rolling off the rims? That is not how tires typically fail nor is there any reason to believe a tire with a higher load rating would somehow do better. In fact the opposite might be true. When I had 19.5 wheels and tires, there was a minimum of I believe 60 psi to be sure the tires stayed on the rims.

No one can argue with a recommendation to increase a safety margin, but there is no basis in fact. This is like recommending oil changes at twice the manufacturer's specs. There is nothing harmful, just no facts to justify the recommendation.

I had a tire "roll off the rim" (break the bead). I was at max for those tires.
Tires that are loaded at/near max will be placing significant stress on the sidewall which certainly could cause this type of failure.
Moved to heavier Load Index and it never happened again.

I can assure you, a tire failure when loaded with a TC is not fun.

[CapriRacer]

10%??? How abut 15%?

For the past 25 years, the major tire manufacturer I worked for has insisted that they will not supply a tire to any vehicle manufacturer who specs the tires at more than 85% of its rated capacity. That was based on a survey of our internal records of tire returns and the published specs of the vehicle those tires were supplied to. What we found was when a vehicle manufacturer spec'd tires no more than 85%, the failure rate was almost non-existent. This was prompted by a problem we had with an RV manufacturer.

This was confirmed by the Ford/Firestone situation shortly thereafter and it appears that other tire manufacturers and other vehicle manufacturers had similar experiences, because AFTER the Ford/Firestone thing, vehicle manufacturers started specifying larger tires.

[JimK-NY]

Ski Pro 3 wrote:
Running close to max on the tires is risky. It leaves you almost no room for emergencies such as a pot hole, something falls off the vehicle in front of you, even an emergency evasive maneuver could cause a tire to roll off the rim if it's at it's rated or close to.

Leave yourself some margin between rated and actual loads on your tires. 10% maybe.

Again, LT tires are rated for continuous use at full load. A safety margin is built into the load ratings.

If you want some extra "margin" of safety, why pick 10%? Why not get a significant margin, say 50%? Also where did you come up with the warning on tires rolling off the rims? That is not how tires typically fail nor is there any reason to believe a tire with a higher load rating would somehow do better. In fact the opposite might be true. When I had 19.5 wheels and tires, there was a minimum of I believe 60 psi to be sure the tires stayed on the rims.

No one can argue with a recommendation to increase a safety margin, but there is no basis in fact. This is like recommending oil changes at twice the manufacturer's specs. There is nothing harmful, just no facts to justify the recommendation.

[Ski_Pro_3]

Running close to max on the tires is risky. It leaves you almost no room for emergencies such as a pot hole, something falls off the vehicle in front of you, even an emergency evasive maneuver could cause a tire to roll off the rim if it's at it's rated or close to.

Leave yourself some margin between rated and actual loads on your tires. 10% maybe.

[dustytires]

I'm a fan of big safety margin on tires. I live in the Southwest, frequently drive across smoking hot roadways for hours, often with 18' cargo trailer in tow. I was running a few different brands with the highest capacity E rated tires I could find. I was always 'just' at their max with a full loaded camper and trailer tongue weight in total. Then on one trip I could feel a growing vibration. At a fueling stop I was shaking wheels, wiggling front suspension components etc trying figure out where it was coming from. Then I saw it.. the tread on one rear tire was getting scarfed bad and the shape of the tire was changing, the tread was not longer totally flat, but had kinda a radius to the tread. I got on the phone and Googled tire shop that was close, and when they pulled it there were multiple blisters inside the delaminating tire. After that trip I got some 19.5 Vision 181 rims and Double Coin RLB 490 and have at least 75 thousand worry free miles and they ain't done yet, I plan to go to 100k and regardless of condition I will discard haha. I rotate about every 5k miles to keep them nice and flat, run 8oz of beads in each for balance and the only thing I fear is throwing my back out every time I rotate them!

[billtex]

Aruba, you don’t really say in your OP, but what are you running for tires/wheel?

Looks like they are rated at 2535# each?

You can do way better than that without going to 19.5’s

I am running 295-75-16 LI 129 rated at 3950# ea on stock steel wheels.

Please provide some more details on what you have now and we can make a better recommendation.

[mbloof]

I also went extreme and upgraded to 19.5" wheels and class H tires.

I think technically my rear end is now the weakest link in the rear. 🙂


- Mark0.

[Artum_Snowbird]

I never had a problem, but I was always on the comfortable side too. I think it might help to consider whether your use is mild, solid roads, etc... or extreme, rough and sharp surfaces, downhill loading, sideways loading.

[KD4UPL]

If you are under and don't add anymore weight like pets, passengers, or extra gear I would just drive it. When I had my camper on a SRW 3500 I was basically at the tire rating. I had no problems. They were Bridgestone Duravis which is considered a commercial tire. If you were right at the limits of cheap off brand tires that might be one thing but you're running Michelins so I think you should be good.
If you want to upgrade your tires so much the better I guess.

[JimK-NY]

Truck tires are rated to carry the full load continuously for the life of the tire. Just be sure to inflate properly and always maintain that pressure.

I also found another way to buy some peace of mind. At about 30K miles, I rotated the rear tires to the front. I rotated the spare to the rear and bought a new rear tire. One of the former front tires became the spare and I eventually discarded the other tire. On the next 30K cycle, I bought two new tires for the rear.