correct tire pressure

jdux999 · 10-07-2018, 03:35 PM

Hello All. I know I've seen this web address listed somewhere but can't find it now. I weighed my Redhawk and I want to know how to determine the correct tire pressure by axle. I think I've seen somewhere that you can't go by the door sticker because the weight on the axle could be very different from rig to rig. Any thoughts about this?

WinnieView · 10-07-2018, 03:48 PM

There are many opinions but we use what's on the door sticker.

Here is one of the many inflation tables;

https://rvsafety.com/weighing/tire-inflation-tables

Grumpy · 10-07-2018, 03:56 PM

You'll get the best ride if you weigh it and follow the tire manufacturer pressure chart.

When we had our 08 SENECA fully loaded and weighed Michelin said 85 Front 90 Rear and it rode and handled like a dream. ( sorry 2008)...

Mountain Cajun · 10-07-2018, 05:16 PM

Just remember, regular class c’s are on LT tires! LT is for light truck. Light truck tires are for hauling a heavy load part of the time not all of the time like a class c. I’ve ran them at the 80 psi 1- for the weigh and 2- prevent overheating. Now having a Seneca Super C my worries have lessened tremendously.

cabinetmaker · 10-07-2018, 06:06 PM

80 rear 75 front per sticker on door pillar from Ford and Jayco. Be very careful listening to those who say you need to weigh each corner and adjust pressure accordingly. I agree you should weigh each corner to help know how your loaded motorhome weighs but always keep the tires at the highest recommended by Jayco and Ford. Class C's on the Ford F-450 chassis are using LT tires and there isn't much margin like in the bigger Class C Seneca's.

Lower pressure might make the ride better but it will be detrimental to the tires in the long run. Keep them at 80 rear 75 front and you will be fine. Check them regularly or pick you up a TPMS to monitor pressure and tire temps continuously. TST 507 series is what we use.

Tires are important to your safe journey...care and maintenance is a high priority!

Grumpy · 10-07-2018, 07:08 PM

Quote:

Originally Posted by cabinetmaker

Lower pressure might make the ride better but it will be detrimental to the tires in the long run.

Not if Michelin or Goodyear or whomever says otherwise. That's why they all print and publish pressure charts based on the weight carried by the tire.

Per Michelin:
We recommend weighing each axle end separately and using the heaviest end weight to determine the axle's cold inflation tire pressure.

cabinetmaker · 10-07-2018, 07:38 PM

Quote:

Originally Posted by Grumpy

Not if Michelin or Goodyear or whomever says otherwise. That's why they all print and publish pressure charts based on the weight carried by the tire.

Per Michelin:
We recommend weighing each axle end separately and using the heaviest end weight to determine the axle's cold inflation tire pressure.

Safety should be considered above all. Motorhomes when weighed can change drastically from trip to trip. Fuel, water, personnel belongings can change and will make a nightmare out of lowering and raising tire pressure.

Use what’s on the door pillar and be done. Again 80 rear and 75 psi front per Ford and Jayco for OP’s F-450.

Murff · 10-07-2018, 08:14 PM

The door pillar numbers are for what was originally provided by the chassis manufaturer. If the tires have been changed, I would go by the tire makers pressure chart.

Murff

Mountain Cajun · 10-07-2018, 08:18 PM

You run those LT tires less than 80 your gonna have problems. Especially the dually’s!

cabinetmaker · 10-07-2018, 08:45 PM

Quote:

Originally Posted by Murff

The door pillar numbers are for what was originally provided by the chassis manufaturer. If the tires have been changed, I would go by the tire makers pressure chart.

Murff

Murff...Jayco also has a sticker with recommended tire pressure numbers on the pillar. Jayco sticker on pillar is added by Jayco when motorhome is built. Again 80 psi rear 75 psi front. I trust Jayco and Ford over some tire companies generic chart.

Grumpy mentions Michelin. They have had previous blowout problems on the F-450 Chassis. You need to be very careful with tires on the Ford F-450 Chassis with a motorhome sitting on it. It is plenty capable but very close to maximum weights.

Grumpy · 10-08-2018, 07:14 AM

Cabinetmaker, Goodyear says exactly the same thing on their RV site, but I guess the people who make the tires know nothing about them. You may find out you need to increase the pressure too. Over 14 yrs how we loaded our MH's changed very little.

Per Goodyear:

Since RVs can be loaded with many different configurations, the load on each tire will vary. For this reason, actual air pressure required should be determined based on the load on each individual tire. Inflation pressure should be adjusted to handle the tire carrying the heaviest load, and all tires on the axle should be adjusted to this standard.

cabinetmaker · 10-08-2018, 07:38 AM

Quote:

Originally Posted by Grumpy

Cabinetmaker, Goodyear says exactly the same thing on their RV site, but I guess the people who make the tires know nothing about them. You may find out you need to increase the pressure too. Over 14 yrs how we loaded our MH's changed very little.
.

Grumpy...have you ever owned a class c on a F-450 chassis? Sure doesn't sound like it. They are not like class A's or Super C's. You can't increase the pressure beyond what Jayco and Ford recommend on the rear because the tires are only rated to carry a maximum of 80 psi. Changing tire pressure for load is fruitless and dangerous. You should never exceed the maximum pressure on the sidewalls of the tires.

Grumpy · 10-08-2018, 08:02 AM

Quote:

Originally Posted by cabinetmaker

Grumpy...have you ever owned a class c on a F-450 chassis? Sure doesn't sound like it. They are not like class A's or Super C's. You can't increase the pressure beyond what Jayco and Ford recommend on the rear because the tires are only rated to carry a maximum of 80 psi. Changing tire pressure for load is fruitless and dangerous. You should never exceed the maximum pressure on the sidewalls of the tires.

My first unit was a 2001 JAYCO 32' Designer, used it for 7 years.

I agree, but you said 75 in the front which may need to be increased. On both our 2001 and 2008 I was able to reduce pressures since we didn't overload it. Everybody owning a MH needs to get it weighed and don't assume you're good because of the door sticker. Those are based on average assumptions by both FORD and JAYCO. WEIGH IT AFTER LOADING IT AS YOU NORMALLY WOULD,, CHECK THE PRESSURE CHART and go from there.

AKRUEBBE · 10-24-2018, 12:04 PM

Quote:

Originally Posted by Mountain Cajun

You run those LT tires less than 80 your gonna have problems. Especially the dually’s!

My 2017 RAM 3500 dually calls for 80 in the front and 65 in the rear. That's exactly what I inflate them to and find that the entire surface of the tire is making good contact. A SRW RAM calls for just the opposite, 80 in the rear and 65 in the front.

oldmanAZ · 10-24-2018, 01:23 PM

Quote:

Originally Posted by AKRUEBBE

My 2017 RAM 3500 dually calls for 80 in the front and 65 in the rear. That's exactly what I inflate them to and find that the entire surface of the tire is making good contact. A SRW RAM calls for just the opposite, 80 in the rear and 65 in the front.

A CRITICAL issue with dually inflation is to be sure the sidewalls of the two tires don't contact one another. So maybe some add a few extra PSI to help ensure that would not happen.

Marmot · 10-24-2018, 01:56 PM

Completely agree. Great advice.

rogerthedodger · 10-24-2018, 06:59 PM

I’m going to agree and disagree. Max tire pressure is 80psi. However, as in my case, after weighing it, l reduced pressure and got a better ride. I ran 75 front/80 rear, rough roads destroyed my shower door. Then I weighed my Melbourne, we travel light. Now the ride is MUCH smoother, no shattered shower door glass.
Also, I check tire temp at every stop.

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