Another Successful 15" to 16" Upgrade

[ROBERTSUNRUS]

Originally Posted by Ag&Au

"Would the full rated pressure enable the remaining tire to have a chance to carry the load to a safe stop better than it has less pressure?"

The answer to this question is obviously - YES.

Ken

Hi, according to the tire pressure to weight chart, I could run 35 lbs in my tires. [6300 lbs GVWR] No way that's going to happen. If I had a flat with my tires set at 35 lbs, the remaining tire would be almost on the rim.

[Steamy1]

Also suggest to make sure that the wheels have the rating to carry the loads and to use high-pressure metal valve stems, if you do make a change. I converted to the Michelin LTX M/S 225/75R16E and run at 80PSI. The metal valves are much safer at those pressures.

[10Smiles]

It's interesting what some say about it being best to run at maximum pressure on your trailer tires. As stated earlier, I am currently running at 65 psi on my new Michelin LT225/75R16 tires. On our first (and only) trip, the tire temperature was noticeably cooler than with the GYMs at the same pressure (actually cool to the touch after running at 60ish mph for a half hour or more).

My Van (Cheverolet Express 2500) has the same tires on it as the trailer (that's kind of handy too, even though the lug pattern is different - in a pinch I guess I could have the Van spare mounted to a trailer wheel). Anyway, the tire inflation tag for the Van says to run the rear tires at 80 psi and the front tires at 55 psi. So it is "legal" to run at less than the maximum pressure on tires. For the Van, I expect that if I ran at the higher pressure than the load requires, the wear would be uneven (in the middle) - even though the front tires don't wear very fast anyway. Also, I would expect that the breaking would be less efficient since there would be less of a tire patch in contact with the road.

Just my thoughts. I love the 16" wheels/tires!

[BlackAces]

10Smiles: Your post opens a number of doors for discussion. First off, did your trailer come equipped with Special Trailer (ST) tires? To keep on going with my thought process I’m going to assume the answer will be yes.

To have properly replaced ST tires on your trailer with Light Truck (LT) tires you would have had to equal the load capacity of the OE tires with a suitable sized LT tire.

I only describe applications of options that meet the current standards and requirements.

There is an industry standard called “plus Sizing”. To plus size the OE tires on your trailer you would have to find some LT tires that would provide the load capacity of the OE tires. Rims for those tires would have to support the maximum load capacity and pressure rating of the plus sized tire. A quick check with the vehicle manufacturer would be advisable to confirm that the dimensions of the plus sized tires will fit into the trailer’s wheelwell without any obstructions. A new recommended tire pressure must be established for the LT tires. To do so, a load index table for the LT tires can confirm the amount of air pressure needed to have them equal the load capacity of the OE tires, as determined by the recommended tire pressure for the OE tires depicted on the trailer’s tire placard. Once that process has been completed, an auxiliary tire placard can be printed and affixed next to the OE tire placard. Notations should also be made in the vehicle’s owner’s manual to reflect the size of the plus sized tires and their recommended tire pressure.

The predetermined tire pressures for your van’s tires takes a different path. The vehicle manufacturer has to take into consideration predicted loads and then set recommended tire pressures accordingly, with a minimum of 6% load capacity reserves. It’s very important to understand this, vehicle manufacturers, SET RECOMMENDED TIRE PRESSURES. Recommended = CORRECT! Vehicle owner’s manuals will have acceptable conditions for manipulation of recommended tire pressures.

BlackAces

[Ag&Au]

Originally Posted by 10Smiles

It's interesting what some say about it being best to run at maximum pressure on your trailer tires. As stated earlier, I am currently running at 65 psi on my new Michelin LT225/75R16 tires. On our first (and only) trip, the tire temperature was noticeably cooler than with the GYMs at the same pressure (actually cool to the touch after running at 60ish mph for a half hour or more).

My Van (Cheverolet Express 2500) has the same tires on it as the trailer (that's kind of handy too, even though the lug pattern is different - in a pinch I guess I could have the Van spare mounted to a trailer wheel). Anyway, the tire inflation tag for the Van says to run the rear tires at 80 psi and the front tires at 55 psi. So it is "legal" to run at less than the maximum pressure on tires. For the Van, I expect that if I ran at the higher pressure than the load requires, the wear would be uneven (in the middle) - even though the front tires don't wear very fast anyway. Also, I would expect that the breaking would be less efficient since there would be less of a tire patch in contact with the road.

Just my thoughts. I love the 16" wheels/tires!

The reason for max pressure does not carry over to 4 wheeled automobiles and trucks, or for that matter, single axle trailers. The tires on a 2 or more axle trailer are subjected to significant sideways forces whenever the trailer is turned. these sideways forces cause the sidewalls of the tires to flex much more than would a tire going straight down the road. Therefor you cannot transfer pressure versus temperature experiences from a tow vehicle to a multi axle trailer.

Ken

[dkottum]

10Smiles, I agree, those 16" Michelins inspire great confidence.

I run mine at 80 psi because, outside of online opinions (and we know what that's worth), Airstream puts 80 psi as the correct tire pressure for these very tires on their Eddie Bauer model. My 25' is virtually the same trailer, with the same load limits. So for me that's where they should be inflated. Simple.

Seems to me you ought to consider this tire pressure as well, seeing your trailer is even heavier, although still an Airstream with its unique characteristics. But that's just another online opinion, isn't it.

doug k

[MaxTow]

Originally Posted by dkottum

10Smiles, I agree, those 16" Michelins inspire great confidence.

I run mine at 80 psi because, outside of online opinions (and we know what that's worth), Airstream puts 80 psi as the correct tire pressure for these very tires on their Eddie Bauer model. My 25' is virtually the same trailer, with the same load limits. So for me that's where they should be inflated. Simple.

Seems to me you ought to consider this tire pressure as well, seeing your trailer is even heavier, although still an Airstream with its unique characteristics. But that's just another online opinion, isn't it.

doug k

There seems to be a good body of evidence that running tandom trailers at maximum tire pressure is the correct thing to do...it's been recommended by the handful of tire engineers that I've seen post to various forums, and at least both of my trailers that I have owned have both had the maximum tire pressure listed as the suggested air pressure.

I believe with the 16" Michelins, even though 80psi results in higher load rating than required, it's still the recommended pressure from Airstream?

Can anybody point to a trailer manufacturer who recommends less that max pressure?

[CapriRacer]

Originally Posted by MaxTow

.........it's been recommended by the handful of tire engineers that I've seen post to various forums......

And the reason you will see us do that is: With almost no exception, the tires being used (or considered) are marginal and the situation requires just about all the load carrying capacity of the tire = maximum pressure.

If we were discussing a sitaution where the tires are much larger (in terms of load carrying capacity) than they need to be, you would find us suggesting a different approach using lower than amximum pressures. That's the sitauioon on many trucks - and will NOT find us recommending maximum pressures carte blanche.