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View Full Version : tire pressure vs. weight- the correct answer


jfaberna
10-01-2015, 01:58 AM
I've been riding around with maximum pressures in my tires to be safe. At the recent National MOC rally, I had my truck and trailer weighed by tire position to see what the facts really were.

My measurements all came out really good, thanks in part to my DRW TV and G614 tires. However, I found out that at my current weight I could reduce the pressure in my G614s to 95-100 psi instead of 110 psi, which is the maximum. Trey Selman from RV Safety showed me the tire pressure recommended chart for both my truck and trailer based on my weight. They add 5 psi for safety and this will allow me to run 95-100 psi and decrease uneven wear in the tires and reduce the chance of impact damage to the tires by potholes, etc.

I also can reduce my TV tire pressures to provide a smoother ride.

Best $60 I've spent.

I also found out that the CAT public scales don't really help RVers because our weight is uneven across the axle. The fridge side is always the heaviest. So my pressures are set for the heaviest side and not the average.

DQDick
10-01-2015, 02:53 AM
I have always run mine at 106-108# even though I could use less. Better milage and no problem with tire wear or damage for me anyway.

bethandkevin
10-01-2015, 03:21 AM
105#. I like the infomercial by-line "Set it and forget it!".

richfaa
10-01-2015, 06:12 AM
Yes one can learn a lot by being weighed .We do the same thing run the G6-14s at 105psi.Truck 65 psi front and 60 psi on the dualies.

CalandLinda
10-03-2015, 08:02 AM
Vehicle manufacturers set recommended tire inflation pressures for all Original Equipment (OE) tires. By regulations they are the only ones responsible for that action.

The recommended tire inflation pressures set by the vehicle manufacturer becomes the minimum standard for all subsequent tire fitments to that vehicle. In other words the load capacity of the OE tires must be maintained because they were established as appropriate for that vehicle. So, if OE tires provided 3420# of load capacity the new recommended tire pressures for G614 replacements must equal or exceed 3420# by inflation. That would be about 96 psi. To get a little extra from the tire Iíd go to 100 psi but 96 is the minimum according to the G614 load chart.

There are no provisions anywhere in the regulations or tire industry standards that allow less tire inflation pressures than those established for the OE tires and their replacements. Of course there are situations outside of the normal operating parameters but they are few and usually.

Setting RV trailer tire inflation pressures to accommodate the load carried is a poor recommendation by whoever makes it. A 1 psi loss of inflation pressure will cause such tires to be overloaded. You can lose a single psi by hitting a curb or pothole or just dropping off the slab you were parked on all weekend. Sure, itís uncommon but it can happen.

CalandLinda
10-03-2015, 08:05 AM
Vehicle manufacturers set recommended tire inflation pressures for all Original Equipment (OE) tires. By regulations they are the only ones responsible for that action.

The recommended tire inflation pressures set by the vehicle manufacturer becomes the minimum standard for all subsequent tire fitments to that vehicle. In other words the load capacity of the OE tires must be maintained because they were established as appropriate for that vehicle. So, if OE tires provided 3420# of load capacity the new recommended tire pressures for G614 replacements must equal or exceed 3420# by inflation. That would be about 96 psi. To get a little extra from the tire Iíd go to 100 psi but 96 is the minimum according to the G614 load chart.

There are no provisions anywhere in the regulations or tire industry standards that allow less tire inflation pressures than those established for the OE tires and their replacements. Of course there are situations outside of the normal operating parameters but they are few and unusual.

Setting RV trailer tire inflation pressures to accommodate the load carried is a poor recommendation by whoever makes it. A 1 psi loss of inflation pressure will cause such tires to be overloaded. You can lose a single psi by hitting a curb or pothole or just dropping off the slab you were parked on all weekend. Sure, itís uncommon but it can happen.

WeBeFulltime
10-03-2015, 04:16 PM
Actually CAT scales can be used to get individual tire weights. Weigh the Fiver normally and then pull around again and put the tires on one side off the scale and then split the two remaining on the scale between two platforms.

Should only be simple math from there.

Second time on the scale is considered re-weigh.....not sure what the charge is now but used to be $1.00 for re-weigh.

Entire process less than $20.00.

DonandBonnie
10-04-2015, 02:58 AM
As mentioned in the first post, the RV weighing folks include a 5 lb. "fudge factor" in their pressure recommendation. That means that the 1 lb. pressure drop also mentioned will probably not be an issue. For us, the pressures recommended was the door sticker pressure on our truck and 110 on the Big Sky. We asked about running the truck at the tire sidewall pressure. They said that it wasn't a problem per se. At the lesser pressure the ride and tire wear would be best. At the higher pressure fuel mileage would be better, but the ride would be rougher and tire wear might be uneven.

mlh
10-04-2015, 05:14 AM
Thanks CalandLinda. Great information.
Lynwood

Art-n-Marge
10-04-2015, 10:33 AM
I don't have a CAT scale near where I live. I use a moving and storage company nearby that just happens to have a truck scale to measure freight loads for folks they move. They charge me only $10 for all my private measurements since I don't need a certified weight(truck empty, truck loaded, with and without trailer, each axle, each side at front and rear axle, trailer only and one side of each trailer axle front and back. Then I use math to figure other side of the axle weights or truck weights and the pin weight. It's been a while since I last weighed my rig and now that I'm full timing I should really do a recheck.

The first time I ever did this I was overweight at the rear axle and thereby each axle at the rear of the trucks. Then I did some work on the rear truck axle springs and larger capacity tires and wheels and now all is good. But I do need a recheck since it's been a while and we are now fulltiming. I'm not too concerned since I believe since we started full timing we removed a lot of stuff we didn't use much. Since we replaced that removed stuff with more important full timing stuff, we need to reweigh.

cw3jason
10-12-2015, 03:54 AM
quote:Originally posted by jfaberna

I've been riding around with maximum pressures in my tires to be safe. At the recent National MOC rally, I had my truck and trailer weighed by tire position to see what the facts really were.

My measurements all came out really good, thanks in part to my DRW TV and G614 tires. However, I found out that at my current weight I could reduce the pressure in my G614s to 95-100 psi instead of 110 psi, which is the maximum. Trey Selman from RV Safety showed me the tire pressure recommended chart for both my truck and trailer based on my weight. They add 5 psi for safety and this will allow me to run 95-100 psi and decrease uneven wear in the tires and reduce the chance of impact damage to the tires by potholes, etc.

I also can reduce my TV tire pressures to provide a smoother ride.

Best $60 I've spent.

I also found out that the CAT public scales don't really help RVers because our weight is uneven across the axle. The fridge side is always the heaviest. So my pressures are set for the heaviest side and not the average.


Totally agree! They were great. It was very comforting to find out I am within all my numbers and I to am running to much air in my tow vehicle.

dieselguy
10-12-2015, 09:04 AM
Quote "Setting RV trailer tire inflation pressures to accommodate the load carried is a poor recommendation by whoever makes it."
What ever floats your boat ... lots of people and businesses towing use inflation charts. If I ran max sidewall psi on my truck, I'd wear the center tread off my tires way before the edge tread. Un-needed rock hard inflation pressure jolts the heck out of what you're hauling. According to my TPMS ... I gain @8psi on a hot day once I get going down the road. I've often wondered how that figures in.

bncinwv
10-12-2015, 09:19 AM
I agree dieselguy, if that was the case, why would the tire manufacturers waste time and money by publishing load inflation charts? I go by the chart and typically add about 5 psi to the recommendation simply because I choose to do so.
Bingo

davidaf
10-12-2015, 11:50 AM
Art where is that scale at? I'm due for a another trip to the scales but don't want to drive out to Ontario to do it.

quote:Originally posted by Art-n-Marge

I don't have a CAT scale near where I live. I use a moving and storage company nearby that just happens to have a truck scale to measure freight loads for folks they move. They charge me only $10 for all my private measurements since I don't need a certified weight(truck empty, truck loaded, with and without trailer, each axle, each side at front and rear axle, trailer only and one side of each trailer axle front and back. Then I use math to figure other side of the axle weights or truck weights and the pin weight. It's been a while since I last weighed my rig and now that I'm full timing I should really do a recheck.

The first time I ever did this I was overweight at the rear axle and thereby each axle at the rear of the trucks. Then I did some work on the rear truck axle springs and larger capacity tires and wheels and now all is good. But I do need a recheck since it's been a while and we are now fulltiming. I'm not too concerned since I believe since we started full timing we removed a lot of stuff we didn't use much. Since we replaced that removed stuff with more important full timing stuff, we need to reweigh.

Phil P
10-12-2015, 02:55 PM
Hi

The early production run of the Goodyear G-614 had uneven tread wear where the outside edges of the tread wore faster than the rest of the tire. This commonly is the result of low tire pressure but I have always run ours at 110 Psi cold.

When I got my second set of G-614 tires my commercial truck tire dealer recommended keeping them at 110 Psi and so fare with balanced wheels I donít have any unusual wear and now have about 25,000 miles on the second set. I have 85,000 miles on the trailer.

I run the tire pressures listed on the truck door post in the TV tires and commonly get 65,000 out of a set of tires. At 149,000 miles I am on my third set of TV tires.

Phil P

MP1
11-13-2015, 01:24 PM
I run my G614's at 105 and use a TireMinder system to monitor them. I had my rig weighed at the rally ...year before last. They recommended 60 psi for the front tires and 80 for the rear...when towing. I have a 2011 Dodge 2500 4x and when NOT towing it rides very hard. In this regard, I carry a CO2 air system with me which allows me...when not towing... to reduce the rear tires to 45 psi for a more comfortable ride...and then increase the pressure using the CO2 air system to 80 psi ...before we tow again. To increase the pressure from 45 to 80 psi takes 4 minutes per tire.

PeteandJoan
11-14-2015, 04:28 PM
Some really informative stuff here on tires. I am really interested in tire tips since I have replaced quite a few tires on my last 5ver. We recently purchased a new monty but as you know they come with ST Trailer King tires. China I think. I always wanted a G-rated tire so I don't have to buy tires every time I turn around. What are you guys running.....besides Goodyear 614's? I have no problem with Goodyear, just wanted to get opinions on some others as well. Probably end up with 614's.

PeteandJoan
11-14-2015, 05:14 PM
Forget my earlier post...I found all the info on another post. Just didn't look long enough.

Ozz
11-15-2015, 01:12 AM
quote:Originally posted by MP1

I run my G614's at 105 and use a TireMinder system to monitor them. I had my rig weighed at the rally ...year before last. They recommended 60 psi for the front tires and 80 for the rear...when towing. I have a 2011 Dodge 2500 4x and when NOT towing it rides very hard. In this regard, I carry a CO2 air system with me which allows me...when not towing... to reduce the rear tires to 45 psi for a more comfortable ride...and then increase the pressure using the CO2 air system to 80 psi ...before we tow again. To increase the pressure from 45 to 80 psi takes 4 minutes per tire.


Miles, I too carry the CO2 for the same reason. Fast, silent and powerful CO2 system. I have a 5# Bottle with compound regulator gauges attached with a bracket to my tool box in the truck. I don't know why more folks don't use this system. I also have a Viair 450 hard-wired and a 2.5 gallon tank under the truck, but the CO2 system if far faster and more convenient.
Stay safe out there.
Ozz