Tires, tires, tires

[Shorty Cox]

There always seems to be a thread about tires. I’ve read them all. Tires, Tires, Tires, ST vs LT. One can read the side wall and learn the tire’s maximum weight load capacity range at cold air pressure. My question is, how do you determine the actual weight each tire is holding up? What formula do you use? I know what my "dressed out" RV weighs, I know what my "dressed out" TV weighs. How do I determine how much weight each tire is carrying? I would think that info would be helpful in determining the load range of a tire.

Shorty

[eldermike]

Trailer weight minus tongue weight divided by the number of trailer tires.

[newbold1]

That is assuming that the load is well balanced. If not, it is possible that some wheels are carrying more of the load than other wheels.

[namusmc65]

Find you a DOT person with a set of portable scales. That is the only accurate way to see what each tire is carrying. They usually are more than glad to weigh your unit as long as they are not really busy.

[wwsmith111]

You can weigh it twice on a CAT scale assuming there is a little room off to the side of the scale. The first time put one side of your rig off the to the side of the scale (i.e. only the tires on one side of your rig will be on the scale) and weigh it with the tires on different platforms. Tell the operator you want separate platform readouts rather than combined. CAT scales often have four separate platforms. Go inside and get the ticket and then pull around and reweigh it the same way except put the other side of the rig off to the side. Tell them it is a reweigh so that the second time it only costs $1 - $2.

[eldermike]

Originally Posted by newbold1

That is assuming that the load is well balanced. If not, it is possible that some wheels are carrying more of the load than other wheels.

Trailer axles are so close together that the net effect of loading differences is diffrent tongue weights with very little if any load difference to individual tire.

[spoon059]

Portable scales are the easiest. For me though, I prefer to purchase trailer tires that are vastly oversized for my needs. My current trailer has a 7500 lbs max weight. My tires are rated at either 2600 or 2800 lbs each (I don't remember which). That means that my tires are rated for about 3000 lbs MORE than it weighs. It cost $6 per tire to go up to D weight rating.

[Shorty Cox]

The reason I ask. I'm going to purchase a set of tires for my 5er before next spring. I've been looking and pricing. I've calculated that each of my RV tires is carrying 2,121 pounds of weight hence, Load Range G tires would be overkill if I'm thinking correct and a waste of money.

[RUSSELL5000]

Shorty Cox, I am into this RV thing for my second year, so am pretty much a newby. I must have read the same threads you did - quite confusing. I settled on looking for tires that would carry 80% of what they are rated for at a maximum. Given that, I also went toward LT tires.

My trailer cm with 15 inch load range D ST tires that the specs say weigh 28 lbs each. I replaced with 16 inch load range E ST tires the specs say weigh 36 lbs each. The new tires are one inch in diameter bigger than original and fit just fine. The new tires are carrying around 78% of their capacity. The cost of the new tires is $145 each versus the cost of the cheapo ST tires the trailer came with at $85 each. Still, the cost compares favorably to the Maxxis trailer tire, the only ST tire I would consider.

I note the trailer tires always run cooler than the truck tires.

That is how I thought through the issue.

[RUSSELL5000]

I meant say that I replaced with 16 inch LT tires, not ST tires.

[Shorty Cox]

Russel, I like you’re thinking. I am convinced that the more you read on here about tires the more confusing it becomes.

To make this tire thing even more complicated, one has to consider the RV wheels limitations. My RV has 16inch “SENDEL” wheels. I contacted the Manufacturer in an attempt to learn the max air pressure the wheel is rated. Below is the response I received.
“Max air PSI is 110lbs. You can run most load range E tires some a little stronger please look at the specs closely. Load range G can get you into some issues because it exceeds the wheels' max loads. What happens if you run load G tires is that the sidewall of the tire is so excessively stiff that it fatigues the bead seat area of the wheel which leads to potential cracks that leak air. The way the wheels are tested is that at 20% over the approved limit the wheel has to be able to handle a range of stresses. The Tire is responsible for absorbing a certain amount. When an excessively stiff or over-strong tire gets put in there is no longer any tire absorption which will prematurely fatigue the wheel.”

Shorty

[muelldawg]

Eldermike, you are right on. Your formula reminded me to subtract the tongue weight. Thanks. We all get excited on the tire issue.