Things to know about trailer tires

[bayoubuggie]

Wow, lots of great info. Just to get this straight, if the max tire pressure on the sidewall is 50psi should that be the pressure before loading the TT or after I load it up?

[Herk7769]

Originally Posted by bayoubuggie

Wow, lots of great info. Just to get this straight, if the max tire pressure on the sidewall is 50psi should that be the pressure before loading the TT or after I load it up?

The Cold Inflation Pressure (sidewall 50 PSI) will NOT change loaded or unloaded. The only thing that changes between empty and loaded is the amount of tread in actual contact with the road. The pressure stays the same.

It is Pounds Per Square Inch. More load; more square inches; same PSI.

ALWAYS set pressure cold (before you drive the first mile) and best done first thing in the AM before the sun starts heating up the south facing tires.

For the purists; the North facing tires in the Southern Hemisphere.

[OldCoot]

Originally Posted by herk7769

...For the purists; the North facing tires in the Southern Hemisphere.

For me it's the East facing tires before the sun gets high enough to shine over my truck and on the tires.

[Tireman9]

Originally Posted by bayoubuggie

Wow, lots of great info. Just to get this straight, if the max tire pressure on the sidewall is 50psi should that be the pressure before loading the TT or after I load it up?

The pressure on your ST or LT tires is the one associated with the max load

for example if your tire said "2000 lbs max load at 56 psi" then I am saying that to get the best durability you need to confirm two things.

1. The maximum load on the most heavy loaded tire MUST be below 2,000# and many strongly recommend below 1,700 and no more than 1800#

2. For TT with two or more axles you should set the cold inflation to 56 psi for the example tire or in your case 50 psi if that is the number molded on the sidewall, to have the lowest inter-ply shear. (This shear is the force at the belt edge trying to tear the belts and tread off the carcass whenever you turn any corner.


Now go read your tire and then get the actual tire loads when you have the trailer fully loaded (food, water, clothes etc)
This link shows how to calculate the individual tire loads. Don't be put off by it being "5th wheel. The math is the same.


You can PM me if you have questions

[bayoubuggie]

Thanks, got the info off of the tire sidewall (1760# @ 50 psi), now just need to load up and find some scales. I can already see my TT loaded up is pushing my tires limits.

[Mike Bullard]

Has anyone ever given thought that trailer tires are of less quality than passenger tires? That they may be made to DOT standards that are well below the DOT standards of passenger tires? Compare the weight of both.... the passenger tire weighs more... i.e. has stronger belts and sidewall components. If you are REALLY a non believer, cut sections (from bead to bead) with a metal band saw, buff the cut surfaces and compare the components in the tire. I have driven on trailer tires that were pathetic and changed to passenger. In every case, without fail, the passenger significantly out performed.

[Canonman]

I'd like to hear what Tireman 9 thinks about using passenger tires. My ST tires are wearing from both shoulders or from the outside in. The driver side rear is worse than the others. I have not rotated them yet but plan to when we store the TT this weekend. Pressure in all four has been checked and double checked just to be sure it's not under inflation. I've had the alignment checked and after $250 they tell me that it was just fine. If I'm buying tires soon I'd like to know if the specialty trailer tire is the only option.
Thanks forthe all the help

[BarryD0706]

Originally Posted by Canonman

I'd like to hear what Tireman 9 thinks about using passenger tires.

He's already spoken about that. Just do a search.

[Herk7769]

Originally Posted by Mike Bullard

Has anyone ever given thought that trailer tires are of less quality than passenger tires? That they may be made to DOT standards that are well below the DOT standards of passenger tires? Compare the weight of both.... the passenger tire weighs more... i.e. has stronger belts and sidewall components. If you are REALLY a non believer, cut sections (from bead to bead) with a metal band saw, buff the cut surfaces and compare the components in the tire. I have driven on trailer tires that were pathetic and changed to passenger. In every case, without fail, the passenger significantly out performed.

Mike, I am pretty sure this is not true.

Trailer tires (ST) are made specifically to be installed on a trailer. They have lower rolling friction (better gas mileage), stiffer sidewalls (for hard twisting turns), and more lubricants in the rubber (to keep them flexible since they sit more often than they roll).

Passenger tires (P) are the worst possible choice for a trailer as they have the lowest load carrying ability of all tire types. "Light Truck" (LT) tires of the correct load range would be a much better choice if you insist on not using the proper tires on your trailer.

If you have any further questions, feel free to contact:

Walter C. Cannon
Executive Director
RV Safety & Education Foundation
321-453-7673
Fax 321-453-3853

[Herk7769]

Originally Posted by Canonman

My ST tires are wearing from both shoulders or from the outside in.

I suggest you weigh your camper. This wear pattern is typical for under inflation based on the actual weight on the tires. If you are already at your maximum tire pressure, your camper is overloaded.

[Canonman]

Thanks Herk, I've checked and we're 5300# dry and under #6500 with DW's closet full and pantry stocked. We travel dry to the destination then fill the fresh tank. I can't remember the tire load max (these are the factory originals) but will check when I get home I'm definitely the "Edge Wear" example. Just the DW and myself so I don't think we're overloaded but worth an easy look. TT is 24' and with double axels I would think pretty well set up. Is it possible the extra weight of the slide over those tires would cause the problem more so on that side?

[Mike Bullard]

Originally Posted by herk7769

Mike, I am pretty sure this is not true.

Trailer tires (ST) are made specifically to be installed on a trailer. They have lower rolling friction (better gas mileage), stiffer sidewalls (for hard twisting turns), and more lubricants in the rubber (to keep them flexible since they sit more often than they roll).

Passenger tires (P) are the worst possible choice for a trailer as they have the lowest load carrying ability of all tire types. "Light Truck" (LT) tires of the correct load range would be a much better choice if you insist on not using the proper tires on your trailer.

If you have any further questions, feel free to contact:

Walter C. Cannon
Executive Director
RV Safety & Education Foundation
321-453-7673
Fax 321-453-3853

Walter,
You need to "section" and buff each type of tire and form your own opinion. I can tell you from my experience passenger tires have a stronger bead, higher stiffer bead filler, heaver polyester sidewall with higher end count, heaver/wider steel belts with higher end count. The tread compounds contain higher concentrations of carbon black and shed water more efficiently. Passenger tires also have significantly better ride characteristics such as radial forces, lateral forces and conicity forces. Claims of heat buildup are basically a mute issue since the bias tires have been replaced by radial tires. Again, from my experience, and my observations from tire sections, passenger tires are significantly better. I actually suspect that since the quality standards seem to be worse than passenger tires they (trailer tires) are an outlet for poor quality ingredients. One glaring fact remains, a "blow out" in a passenger vehicle is truly life threatening. Whereas a blowout on a trailer is dangerous... it is not as life threatening.

Walter, I believe in my personal experiences. I would seriously appreciate any actual factual opinion otherwise. Section a few tires and tell me what you see.

[Herk7769]

Originally Posted by Mike Bullard

Walter,
You need to "section" and buff each type of tire and form your own opinion. I can tell you from my experience passenger tires have a stronger bead, higher stiffer bead filler, heaver polyester sidewall with higher end count, heaver/wider steel belts with higher end count. The tread compounds contain higher concentrations of carbon black and shed water more efficiently. Passenger tires also have significantly better ride characteristics such as radial forces, lateral forces and conicity forces. Claims of heat buildup are basically a mute issue since the bias tires have been replaced by radial tires. Again, from my experience, and my observations from tire sections, passenger tires are significantly better. I actually suspect that since the quality standards seem to be worse than passenger tires they (trailer tires) are an outlet for poor quality ingredients. One glaring fact remains, a "blow out" in a passenger vehicle is truly life threatening. Whereas a blowout on a trailer is dangerous... it is not as life threatening.

Walter, I believe in my personal experiences. I would seriously appreciate any actual factual opinion otherwise. Section a few tires and tell me what you see.

I am not Walter.

Walter is an RV safety engineer at the Center for RV safety and Education.
If you won't buy advice from a real expert; then you certainly don't want to hear anything "I" would have to say.
Herk

[Herk7769]

Originally Posted by Canonman

Thanks Herk, I've checked and we're 5300# dry and under #6500 with DW's closet full and pantry stocked. We travel dry to the destination then fill the fresh tank. I can't remember the tire load max (these are the factory originals) but will check when I get home I'm definitely the "Edge Wear" example. Just the DW and myself so I don't think we're overloaded but worth an easy look. TT is 24' and with double axels I would think pretty well set up. Is it possible the extra weight of the slide over those tires would cause the problem more so on that side?

Certainly!

In fact the wear patterns on my 5th wheel are pretty interesting.

I have been inflating all 4 tires to the same air pressure. However, I just got back from an 8,000 mile cross country trip and due to the angle of my 5th wheel when connected, the leading axle's tires are showing slightly OVER inflated wear while the trailing axle's tires are showing slightly UNDER inflated wear.

This spring I will be weighing each axle individually and setting the pressures by axle and not by the aggregate trailer weight (both axles summed together on the scale pad).

[Canonman]

Thanks Herk, really good to get some real world advice. So it's check your tires load range against the TT loaded weight. Rotate front to back and side to side then do the hokey-pokey and when you buy new, buy the right load range ST and GO Camping!
That about it?

[Herk7769]

Originally Posted by Canonman

Thanks Herk, really good to get some real world advice. So it's check your tires load range against the TT loaded weight. Rotate front to back and side to side then do the hokey-pokey and when you buy new, buy the right load range ST and GO Camping!
That about it?

Pretty much. When these Marathons are done (maybe 2 more years); another set of Marathons will go right on. I will try to get another 4 from the Gadsden Alabama plant again (code MD), but I would have no problem buying Goodyear from any plant (even the dreaded Chinese plants).

I went UP one load range (C to D) when I bought the Marathons and will be replacing them with load range D again. There is absolutely NO reason (IMO) to go up more than one. Truly a waste of money. I like the ability to run a higher pressure than needed (up to 10 PSI) in case I need to run at higher than 65 mph for safety reasons (like heavy, high speed traffic). Not saying I will; just that I can.

See the attached tech bulletin from Goodyear for speed rating information on Marathons.

[BigBaron]

Tireman has written about weighing each tire individually. Sometimes the front axle has significantly different loading.
After reading a thread about a fiver that was 1,000 lbs. heavier on the driver side, I think that would be the only way to go.
An LT tire is the only option to an ST, but you have to reduce the load capacity by 10% if using it as a trailer tire.
A pressure monitoring system would be a good idea, too.

[Herk7769]

Originally Posted by BigBaron

Tireman has written about weighing each tire individually. Sometimes the front axle has significantly different loading.
After reading a thread about a fiver that was 1,000 lbs. heavier on the driver side, I think that would be the only way to go.
An LT tire is the only option to an ST, but you have to reduce the load capacity by 10% if using it as a trailer tire.
A pressure monitoring system would be a good idea, too.

Also very good advice...

[Mike Bullard]

I will not get into my credentials other than saying I personally have nearly 50 years of experience with tires... from development, manufacturing, testing and using.

There is a lot of miss information and sales hype regarding trailer tires. In my personal opinion, they are significantly inferior to equivalent passenger tires.

A case in point, the rear of a front wheel drive vehicle is nothing more than a trailer. Those tires will see the same forces, wear and stress as those on a trailer. Why is it those passenger tires outlast trailer tires by tens of thousands of miles?

Passenger tires are produced to a better standard.

If you doubt it, cut sections of both tires and compare for yourself.

[Herk7769]

Originally Posted by Mike Bullard

I will not get into my credentials other than saying I personally have nearly 50 years of experience with tires... from development, manufacturing, testing and using.

There is a lot of miss information and sales hype regarding trailer tires. In my personal opinion, they are significantly inferior to equivalent passenger tires.

A case in point, the rear of a front wheel drive vehicle is nothing more than a trailer. Those tires will see the same forces, wear and stress as those on a trailer. Why is it those passenger tires outlast trailer tires by tens of thousands of miles?

Passenger tires are produced to a better standard.

If you doubt it, cut sections of both tires and compare for yourself.

Mike,

Do you still work for Continental Tire? I looked at their web page and they not only do not make an ST tire; they don't even make a true LT tire.

The closest tire with an actual load rating is for an SUV and they stress TRACTION not load carrying capability.

Continental USA Car / Light Truck / SUV -*CrossContact