We are getting ready to take off on our first road trip (I don't think the mile from the dealer counted!). We are a little confused about tire pressure on both the truck and the 5er.
First question - is the PSI listed on the side of the tire the maximum PSI or the recommended? On the truck, the label inside the door lists a different number than what's on the tire. Which one do we follow?
Second question - should the PSI be different when we're towing vs when we're not? In other words, should the tires be more or less inflated when towing?
Third question - on the 5er, both the tire sidewall and the label on the 5er state 110 psi. However, since the day we picked up the rig, the tires have only been inflated to 95. All 4 tires are the same. So this makes me question whether we should leave them at 95 or inflate them to 110?
Any guidance is much appreciated!
Terry and Jo said
04:25 PM Apr 12, 2010
Connie and Tracy,
In my opinion, one always wants to go with the recommendations on the tire itself. After all, the vehicle manufacturer won't really know whose tires are on the vehicle. If I recall correctly, most of the inflation recommendations on the tires are for the maximum tire pressure.
Remember to always check tire pressure when the tire is cold, not after it has been run a while.
As for the truck tires, maximum recommended, although some say they carry 5 pounds less in the tires on the front axle of the truck.
I'm sure others will pitch in with other recommendations.
Drive safe on your upcoming road trip, and enjoy.
Terry
-- Edited by Terry and Jo on Monday 12th of April 2010 04:26:20 PM
Luvglass said
06:28 PM Apr 12, 2010
We run the tire maximum on the trailer and the label recommendations on the truck with the front 5 pounds lighter.
53 Merc said
06:32 PM Apr 12, 2010
Do a search on this forum for tire pressure, and be prepared for lots of information. The pressure stamped on the sidewall of the tire is for carrying capacity for maximum load. Since we don't know what 5er you have, nor how much load you put in it for travel, we can't offer anything except run max pressure.
In my case, I always run at max pressure, to negate the pressure increase due to heat build up while traveling. In doing so, I never have to consult a pressure chart or do anything except see if it has max.
Racerguy said
07:15 PM Apr 12, 2010
What Fred said.
BillA said
08:46 PM Apr 12, 2010
Regarding question one: The manufacturer of the truck has divided the maximum load rating of each axle by the number of tires installed on the axle to arrive at the maximum load each tire must carry. They then have consulted the load/pressure chart for the tires originally installed on the truck to arrive at the minimum inflation pressure required to carry that load. In the case of your axles the maximum loading on the axle is reached before the maximum loading on the tires is reached, therefore you do not need to carry the maximum pressure stamped on the sidewall.
Regarding question two: That is a matter of choice. Carrying the Ford recommended pressure in the tires when running empty (without the fiver or other significant load) is fine. Reducing the tire pressure will improve the ride of the truck when empty but underinflating the tires will create extra heat, irregular wear and in extreme cases tire failure. So you really need to know what the tire loading is when the truck is empty (based on truck scale ticket for each individual axle) and then refer to a pressure/loading chart for the particular tire in question to arrive at the recommended tire pressure for that load.
Regarding question three: Because the loading in your fifth wheel changes frequently depending on the amount of water and supplies onboard, and because loading on each individual tire can vary due to the trailer design and where you stored various items, I would recommend running the tires at the trailer manufacturers recommended pressures which should be at least the minimum required for the maximum load rating of the axle the tire is installed on.
DagoRanch said
08:56 PM Apr 12, 2010
I'll add my 2 cents in for what it's worth, to explain the difference between what the label in the truck says vs what the tire says on the sidewall as it relates to your tow vehicle.
Your tires weight ratings stamped on the tire are based on max inflation. That weight rating goes down as you lower the pressure. The label on the truck only takes into account the weight of the truck without cargo and recommends the best pressure to both support the trucks weight and give a fair balance of ride, wear and gas mileage. The manufacturer leaves it up to the customer to increase inflation as load increases.
It's actually no different than your passenger car. Lot's of modern tires have max pressures of 40-50 psi. Does anyone actually run their tires at that pressure? Is that pressure a recommended pressure for a passenger car? Absolutely not. Recommended pressure would be in the range of about 32 psi. Throw a load of bricks in the trunk and you'd probably want to air up your tires to support the extra weight.
It's the same for your tow vehicle. When you have your 5'er hitched up and loaded with cargo and passengers, ABSOLUTELY inflate them to their maximum pressure stamped on the sidewall. If you're going to be riding around unhitched for an extended amount of time, I'd air back down to the pressure on the truck label. You'll have a much better ride and actually prolong your tread life as an overinflated tire will wear the center down faster and thus decrease the life of your tires.
Now if your just going to the corner market for a few days and don't much care about the rough ride, it won't have much effect, but if you're staying parked for a couple of weeks and are going to tool around exploring in that truck, then I'd definitely be airing down.
Now as far as the trailer is concerned... max pressure at all times. There's nowhere near the wiggle room that the tow vehicle has and if you're loaded up to the GVWR of the trailer then they'll NEED to be at max pressure at all times.
Remember the number one cause for tire failure is under inflation.
So I either explained the discrepancy for you, or confused the heck out of you by now ;) It looks like BillA and I had the same idea!
-- Edited by DagoRanch on Monday 12th of April 2010 08:59:52 PM
contra said
09:33 PM Apr 12, 2010
Thanks to all for the guidance. I THINK I understand better. It sounds like you all agree that the trailer should always be at max inflation. It sounds like when towing, max inflation on the truck is recommended. Thanks Tony for your examples. It makes perfect sense. This is all such a great learning experience, but knowing that we have so much more to learn is a bit intimidating!
We are getting ready to take off on our first road trip (I don't think the mile from the dealer counted!). We are a little confused about tire pressure on both the truck and the 5er.
First question - is the PSI listed on the side of the tire the maximum PSI or the recommended? On the truck, the label inside the door lists a different number than what's on the tire. Which one do we follow?
Second question - should the PSI be different when we're towing vs when we're not? In other words, should the tires be more or less inflated when towing?
Third question - on the 5er, both the tire sidewall and the label on the 5er state 110 psi. However, since the day we picked up the rig, the tires have only been inflated to 95. All 4 tires are the same. So this makes me question whether we should leave them at 95 or inflate them to 110?
Any guidance is much appreciated!
In my opinion, one always wants to go with the recommendations on the tire itself. After all, the vehicle manufacturer won't really know whose tires are on the vehicle. If I recall correctly, most of the inflation recommendations on the tires are for the maximum tire pressure.
Remember to always check tire pressure when the tire is cold, not after it has been run a while.
As for the truck tires, maximum recommended, although some say they carry 5 pounds less in the tires on the front axle of the truck.
I'm sure others will pitch in with other recommendations.
Drive safe on your upcoming road trip, and enjoy.
Terry
-- Edited by Terry and Jo on Monday 12th of April 2010 04:26:20 PM
Your tires weight ratings stamped on the tire are based on max inflation. That weight rating goes down as you lower the pressure. The label on the truck only takes into account the weight of the truck without cargo and recommends the best pressure to both support the trucks weight and give a fair balance of ride, wear and gas mileage. The manufacturer leaves it up to the customer to increase inflation as load increases.
It's actually no different than your passenger car. Lot's of modern tires have max pressures of 40-50 psi. Does anyone actually run their tires at that pressure? Is that pressure a recommended pressure for a passenger car? Absolutely not. Recommended pressure would be in the range of about 32 psi. Throw a load of bricks in the trunk and you'd probably want to air up your tires to support the extra weight.
It's the same for your tow vehicle. When you have your 5'er hitched up and loaded with cargo and passengers, ABSOLUTELY inflate them to their maximum pressure stamped on the sidewall. If you're going to be riding around unhitched for an extended amount of time, I'd air back down to the pressure on the truck label. You'll have a much better ride and actually prolong your tread life as an overinflated tire will wear the center down faster and thus decrease the life of your tires.
Now if your just going to the corner market for a few days and don't much care about the rough ride, it won't have much effect, but if you're staying parked for a couple of weeks and are going to tool around exploring in that truck, then I'd definitely be airing down.
Now as far as the trailer is concerned... max pressure at all times. There's nowhere near the wiggle room that the tow vehicle has and if you're loaded up to the GVWR of the trailer then they'll NEED to be at max pressure at all times.
Remember the number one cause for tire failure is under inflation.
So I either explained the discrepancy for you, or confused the heck out of you by now ;) It looks like BillA and I had the same idea!
-- Edited by DagoRanch on Monday 12th of April 2010 08:59:52 PM
Thanks to all for the guidance. I THINK I understand better. It sounds like you all agree that the trailer should always be at max inflation. It sounds like when towing, max inflation on the truck is recommended. Thanks Tony for your examples. It makes perfect sense. This is all such a great learning experience, but knowing that we have so much more to learn is a bit intimidating!