On my tow vehicle the max cold inflation is 50 psi. Does that mean I should inflate it to 50 psi or a percentage of that. Right now they're at 44lbs. Thank you. Jim
You need to find out what weight your tires need to carry and adjust the pressure accordingly. For example, you weigh your pulling vehicle and trailer and find out by axle what the weights are. You then go to a reference publication (such as the Tire and Rim Handbook), find your tire size, and look of the pressure required for the weight on your axles (tires x 2).
In my case, I have load range E tires. For my vehicle, the doorpost sticker shows 80 psi for the rear tires (3/4 t Suburban). However, if I look at the actual load on the rear axle, plus a reasonable margin of safety, I need only 45 psi when solo and 65 psi when pulling my trailer.
Alan, when you say weigh the trailer to determine the weight for the tow tires, shouldn't I only consider the tongue weight since that is the weight that will actually be placed on my tow vehicle rear axle? In other words, I add the tow vehicle weight to the tongue weight and that should detemine the load I have.
The max cold pressure of 50 psi for your tires should not be exceeded. Look inside the door jamb and the factory size tires are listed along with a recommended psi fill pressure. My door lists 80 psi for the rear tires LT 245-75-16 E rated but that is with a max towing load. Unloaded I run 50-55 psi on those rear tires but air them up to 70 psi when I hook up my '77 Excella 500 31' unit. Tongue wt. is a little over 1,000 lbs. My '92 Chevy K1500 Z71 with LT 265-75-16 tires ran about 41 psi with a max of 55 psi. I would experiment with tire pressure between 45-50 psi to find out how the vehicle rides. If it seems rather harsh then lower the pressure just a little. If it seems squirrelly? then add pressure but no more than 50 psi. cold.
__________________ Craig
AIR #0078
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My Ford Ranger door tag says I should be at 30 psi (not towing) but I listened to "experts" who recommended 36 psi. I now have an "over inflated" wear pattern. The Tire and Rim Handbook can be found at a tire shop? I'd hoped to find it on the 'net but no such luck.
Thirty six psi seems like a good pressure while towing as I have 12,000 miles that way and no blow-outs. Today I had a service station guy tell me to pump the tires up to the 45 psi max while towing. Nah! I don't think I'll try that. I revive this thread to bring this to the attention of new towers to think about. I didn't pay attention to adding more air while towing. I think I lucked out that they were over inflated as it was. Learn from my mistake. Jamie
I agree with davidz71 regarding tire pressures. I tend to lower the psi in our truck when running empty or no trailer, and then adjust tire pressures accordingly to what I may be carrying or towing. Jeff
Tire inflation charts can be found at the manufacturer's web sites. I have found them at Goodyear and Michelin, so I know that they are there.
Get axle weights with the loaded trailer attached to determine proper pressures for the load when towing. Of course, don't go over the maximum pressure on the sidewall. If that is not sufficient for the load, you need to go to a higher load range tire if wheel and axle ratings allow.
Whatever you do, don't allow tires to be underflated for the load carried as they will overheat and fail.
This is one of my favorite subjects. We just got back from the Florida State Rally where I attended a seminar on weight ratings and tire pressures. To properly inflate the tires on the tow vehicle and the trailer you should have each wheel weighed separately. The reason being that there is a difference between the right and left side weight of both vehicles.
On an axle, if one side indicates 35lbs and the other 40lbs, then the pressure for both tires is 40lbs. Also, when determining the proper pressure, find the weight on the chart that is not greater than the weight the tire carries and use that pressure. For example: your tire carries 1690lbs. The chart says
35lbs 45lbs 50lbs
1475 1675 1875
The proper pressure in this case is 50lbs.
The cold pressure on the sidewall is the maximum cold pressure you should carry in the tire. When the tire heats up, the pressure will go up. That is ok. DO NOT LET AIR OUT OF A HOT TIRE TO LOWER IT TO THE MAX RATING!! You will end up with an under inflated tire when it cools, if the chart indicates that is the pressure you should be carrying.
On each travel day, you should check the pressure in your cold tires. If it is 5lbs low and you have to go 10 miles to the gas station to put air in, check the pressure of the warmed up tire and add 5lbs to that. That is the pressure you want pump the tire up to.
While on the road, if you check the pressure of a warm tire and it is above the recommended pressure for the weight it carries, DO NOT LET AIR OUT OF THE TIRE!! You will be under inflated if you do.
You should weigh your tow vehicle loaded with all the stuff you carry on a trip. Weigh it without the trailer attached then with the trailer attached. That way you can get a tongue weight. In both cases, you should have the people in the tow vehicle with whom you normally travel . For instance you and your significant other.
Also note that you can overload the GVW of either your tow vehicle or your trailer and still not overload the axles.
Lastly, check your receiver placard for the maximum tongue weight it can carry and check the hitch ball weight for the weight it can handle. Every hitch ball has the maximum trailer weight stamped on it. Wipe off the grease and make sure yours is designed for the trailer weight you are towing.
Tires:
Tires should not be more than 5-7 years old. Every tire has the week and year it was cast imprinted on the sidewall. Prior to 2000 it was a 3 digit number. 202 indicates week 20 of 1992. In 2000 the number was changed to a 4 digits. 2002 indicates week 20 of 2002.
One of the things to ensure when you buy new tires, in addition to the load range and tire type "LT" or "ST", is that they are not more than 6 months old. Check the age of each tire. Insist on "new" tires. If the tire has sat around in the warehouse for a year, you are buying an old tire even if it has never been on the ground. The rubber ages whether it is being used or not.
DO NOT USE TIRE DRESSING on any tire. The dressings will shorten the life of the tire. They are petroleum based. If you put it on, rub your finger over the tire and look at it. That black stuff is tire residue that is aging your tire as you look at it.
Ok, I'm off my soap box.
Vic
__________________
Vic Smith
WBCCI #6782
31' 78 Airstream Excella 500
2001 Ford Excursion V-10
Reese hitch and dual cam sway control
DO NOT USE TIRE DRESSING on any tire. The dressings will shorten the life of the tire. They are petroleum based. If you put it on, rub your finger over the tire and look at it. That black stuff is tire residue that is aging your tire as you look at it.
Vic
Vic, I went to a tire seminar a few years ago conducted by RV-Self. They pretty much said all the same things you did, except they did recommend one product that contains no petroleum. It called 303 Aerospace Protectant. I have used it on my tires for about 4 years now with no adverse effect. Here is a link to the product.
__________________
Nick Crowhurst, Excella 25 1988, Dodge Ram 2500 Cummins Diesel. England in summer, USA in winter.
"The price of freedom is eternal maintenance."
Vic, I went to a tire seminar a few years ago conducted by RV-Self. They pretty much said all the same things you did, except they did recommend one product that contains no petroleum. It called 303 Aerospace Protectant. I have used it on my tires for about 4 years now with no adverse effect. Here is a link to the product.
Jack,
I attended the same company's seminar at FSR. I remember them mentioning a tire dressing that contained no petroleum, but I couldn't remember it's name. Thanks for bringing it to my attention.
Vic
__________________
Vic Smith
WBCCI #6782
31' 78 Airstream Excella 500
2001 Ford Excursion V-10
Reese hitch and dual cam sway control
I pull a 1985, 25' Sovereign with a 2001 Excursion V-10. My weights loaded are: (including the kitchen sink)
Front two axles (Excursion) = 8,420
Rear two axles (Airstream)= 6,280
I have never placed load cells to determine individual wheel or tongue weights.
I have been running 70 lbs rear, 60 lbs front on the Excursion and 60 lbs all around on the AS.
I drop the Excursion down to 50 front 60 rear w/o the AS.
I have encountered no problems on a 16K mile journey last Spring & Summer.
Am I doing all right or something wrong, per you recently acquired knowledge?
Driftwood,
Without knowing what tires you are running and the load on each of the tires, it would be hard to say. I suspect you are running the pressures a little high. That said, I wouldn't change anything until you get the unit weighed as indicated in my text. It is better to run the pressure too high than too low. Too low is dangerous. Too high may shorten the tire life by wearing the center of the tire more than the edges and the Ex will ride hard... harder than normal. They all ride like a buckboard.
You are doing all right.
Vic
__________________
Vic Smith
WBCCI #6782
31' 78 Airstream Excella 500
2001 Ford Excursion V-10
Reese hitch and dual cam sway control
I just scanned through the posts, and didn't see this mentioned, a lot of people don't realize it.
The wheels your vehicle has on it also have a maximum inflation pressure, for most autos it is 35psi. A light truck, like a F150, or other 1/2 ton van or truck, may be 41 psi. Whichever is the lower pressure, don't go over it. No matter what the other part of the equation says, the tire/wheel assembly only has the max pressure of the lesser of its two parts.
A Ford Ranger should have 35psi front, 30psi rear, depending on year and load.
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