Tire Validation thoughts.

amxpress wrote:


So are you saying that my Maxxis ST tires when inflated cold to 80 psi are not designed to handle the incresed pressures when hot?

I also find your comment about heat, not loads, cause most blow outs. Where may I find these statistics for reference?

to answer your question.. the correct answer is no. especially when the roads are hot, the tire pressure needs to be close to max psi.
this is because low pressure allows the tire to flex more... flexing causes heat... and it is absolutely true that low pressure is the cause of more tire failures than the load or over inflation... with the exception that the load on a tire, heavy load or otherwise, causes flexing of the sidewalls, which builds heat.

this is why when a maximum load is placed on a tire, the maximum pressure is recommended.... and less load, less pressure is required.

on some forum recently, (maybe this one) I wrote something similar to "a tire that goes flat from punctures or from being so low on pressure that it pops off the bead in a tight turn, may be able to be repaired many times over, but any tires that go flat from heat have to be replaced every time"....

over loading is nearly equivalent to over inflating, and its low on the list of tire failure causes, with the exception that overloading causes flexing of the tire, and the less internal pressure the tire has in it, the quicker it builds heat and fails.
so in a sense, the load does have a lot to do with it, but overloading is more relative to the amount of pressure in the tire, rather than what is stamped on the tire.
the main difference between the ST tire (Special Trailer) and a LT tire (Light Truck) is the sidewalls in the st tire is stiffer, so it stands up better and is designed to flex less. low pressure allows it to flex too much.
so keep it aired up and carry the load without having a blowout.

for those that like to run a lower pressure, or have a habit of not checking their tire pressures often, the LT tires will be a better option.
you can run LT tires on a trailer, but its illegal to run ST tires on a truck....

and in addition, for anyone that does have a blow out and doesnt have a spare left, you can limp many miles (50+) on a flat tire without damage to the rim if you keep your speed to less than 10mph... once the vehicle speed reaches 11-12mph, the flat tire will begin to come apart and will soon leave the rim riding on the road surface, rather then the flat tire.
this is directly due to the heat generated by the speed of the flexing...on a hot road surface, the tire rubber may get so hot that it sizzles when you spit on it, but if you keep the friction low, it will hang together.

ST235/80R16 tires. The trip to the scales is on my list. I normally run with in 5psi of max on the tire. I live in Texas, and try to keep the speed limited to 65-70. The tires show a max speed limit rating of 75. I do not have a tpms, but I, will look into them. I have busted Gladiators, lionshead, Carlisle tires. I have not verified the axles on the RV yet, but will. I also plan on measuring my factory rims to know they are correct for the tires. It would be fair to say, I get less than 5000 miles on a tire. The trailer is square behind the truck, no one has ever said different. Hitch wt= 1800# As a follow up, Should I dump the ST tires, and get the LT tires? I'm leaning toward a combo air pressure and ST tire selection s a probabal cause.

I ran LT 16" all season tires on old coach (10,800 dry, 13,800 max, 12,800 fully loaded). 80 psi each morning before leaving. Had no problems in 11 years and 70 mph.

FWIW, the LT tires were NOT some Chinabomb brand. Cooper Discover AT's if memory serves me right.

ST tires are not designed to handle heat buildup, LT tires are. If you have 15 inch rims you can get 113 load range (2550lbs) tires but you may want to go up to 16 inch to get a higher load range rated LT tire.

Heat not load causes most blowouts. If you are not running with low air pressure or driving over the recommended speed for ST tires (the main culprits for ST tire blowouts) then it is may be the heat of the day. Blowouts are a summer event in ST tires. If you are driving 80, on a hot day, with low tire pressure you are headed for a blowout

So are you saying that my Maxxis ST tires when inflated cold to 80 psi are not designed to handle the incresed pressures when hot? This is a concern because we traveled 5400 miles this past August through such hot climates in AZ, NV, NM, TX, etc.
I also find your comment about heat, not loads, cause most blow outs. Where may I find these statistics for reference?

Load G tires (4080-4400 lb capacity) are better suited for heavy loaded 7k axles.

What size axles does your trailer have ??
What size and load range are your OEM tires ??
As was mentioned a 10000 lb trailer can have a 2000 lb hitch leaving 8000 lbs on the axles or 2000 lbs per tire. Now add the 10-15 percent reserve capacity = 2200-2300 lb. No way you need a 4000 lb rated tire for a 10k trailer

Tires on your trailer should have been selected by the trailers axle ratings plus a 10-15 percent reserve capacity. Trailers unlike our trucks can have too much tire for best wear and long term reliability.

The new gen ST tires are rated at 75-81 mph. As long as the tires are pumped to max sidewall pressures they can handle heat issues caused by speed....and Running a lower pressure in the tire can cause it to run hot which leads to throwing the tread belts or interply shear while making those sharp turns backing up or going forward.

We have some very good LT and ST tires out here for specific sizes and loads. Give us some numbers to work with.

ST tires are not designed to handle heat buildup, LT tires are. If you have 15 inch rims you can get 113 load range (2550lbs) tires but you may want to go up to 16 inch to get a higher load range rated LT tire.

Heat not load causes most blowouts. If you are not running with low air pressure or driving over the recommended speed for ST tires (the main culprits for ST tire blowouts) then it is may be the heat of the day. Blowouts are a summer event in ST tires. If you are driving 80, on a hot day, with low tire pressure you are headed for a blowout ;)

Get tires that cover the full GVWR. Forget dry weight.
LT is good in all conditions. ST get 80+ mph speed rated.

You should have said what brand, and whether they were "E" rated ST tires or "E" rated LT tires. I would bet that you're running "E" rated 235/80-16 ST tires.

If it is 9600 lbs. dry, you're probably looking at least 11,000 lbs. loaded and on the road. Even at 12,000 lbs. you should be fine with "E" rated LT tires. They are rated at 3040 lbs. at 80 psi. That gives you 12,000 lbs. carrying capacity. If you weigh 12,000 lbs., you'll be carrying around 2400 lbs. in the bed of the truck leaving less than 10,000 lbs. on the trailer axles. You should be good to go with "E" rated 235/80-16 LT tires.

IMO "G" rated tires would be overkill on your 5th wheel.

That's what I have on my 13,500 pound fiver. You need to get real honest loaded ready to travel weights. Make tire decisions based on that. What axles do you have?

If your trailer is truly 10,000lbs when you are towing, your tires are only holding 7500 to 8000lbs which should be well within the capabilities of a Load Range E tire.

Two things you don’t mention are the pressure you run and a TPMS. Air pressure in the tires needs to be checked as often as your fuel and oil as far as I’m concerned and should be at the maximum rating for the tire if the wheels allow it. A TPMS lets you do so constantly while on the road and is the best money you can invest.

A trip across a scale would be well worth your time and expense too.