correct tire pressure??????

Neville Anderson · Post by **Neville Anderson** » Sat Sep 17, 2005 8:50 am

Question: On our 2005 BF 24' we were advised by the BF dealer to carry 65 # air pressure in all tires. After an oil change by an authorized Ford dealer, I notices on the work order that Ford recommended 65# in the front tires and 90# in the rear. Any info? Thanks. Nevjoy

Bill Ruh · Post by **Bill Ruh** » Sat Sep 17, 2005 11:05 am

Hi Neville,

The tire sidewalls have the maximum pressure on them and you should not exceed it. For an e450 with load range e tires, that's typically 80 psi.

But the only accurate way to set tire pressure is to weigh your motorhome with separate front and back weights and set the tire pressure according to the manufacturer's chart.

For example, our 22' e350 (unloaded with full water) front was 3780lb and back was 6640lb, which calls for 50psi. Loaded, we're in the 55psi range, so that's what I run.

But what I use or what someone else uses or what the door jam says or what ford says or even what born free says is irrelevant to you. The only accurate way to set tire pressure is to weigh your motorhome...

Mel Wilbur · Post by **Mel Wilbur** » Sat Sep 17, 2005 11:28 am

I agree with Sam that you should run 65# in the front and 80# in the rear duals. The only time I would consider any less would be after you had the coach properly weighed with full tanks of fuel, water, lpg and ready to roll with food, clothes, driver and co-pilot on board (your maximum weight) you may find you could safetly run slightly lower pressures based on tire size/weight capacities charts. The ideal way to have the coach weighed is 4 corner weighing, sort of like driving onto heavy duty bathroom scales, unfortunately not always easy to find those facilities.

Bornfree22bft · Post by **Bornfree22bft** » Sat Sep 17, 2005 3:34 pm

I agree with Bill. Get your unit weighed loaded each corner and inflate accordingly.

Neville Anderson · Post by **Neville Anderson** » Sun Sep 18, 2005 8:33 am

Good Morning - I appreciate the fast responses and good info. Our first RV - so many questions. Thank you all. nevjoy

whemme · Post by **whemme** » Sun Sep 18, 2005 11:48 pm

Here is some detailed 4-corner weight data on my Born Free.

2002 BORN FREE 26â€™ RSB MOTOR HOME TIRE INFLATION DATA

Â Â Â Â 1) Left Front Â Â Â Â - 60 PSI
Â Â Â Â Â Â Â Â Â 2) Right Front Â - 55 PSI
Â Â Â Â Â Â Â Â Â 3) Left Rears Â Â Â - 75 PSI
Â Â Â Â Â Â Â Â Â 4) Right Rears - 75 PSI

NOTES: Above calculations based on separate weighing of all four corners of the motorhome with 2 owners in front seats, 55 gallon fuel tank full, 35 gallon fresh water tank full, 6 gallon water heater tank full, and LP tank 1/2 full and on installed Firestone Steeltex R4S LT225/75R16E radial tires.

A) Single tire weight capacity rating @ 80 PSI: 2680 lbs
B) Dual tire weight capacity rating @ 80 PSI: 2470 lbs each

FOUR CORNER WEIGHT OF MOTORHOME

A) Left front - 2070 lbs
> 4040 lbs front axle
B) Right front - 1970 lbs
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â > 13,260 lbs TOTAL
C) Left rear - 4690 lbs
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â > 9220 lbs rear axle
D) Right rear - 4530 lbs

REQUIRED TIRE PRESSURES PER ACTUAL CALCULATION:

1) Left front tire - 56 PSI
2) Right front tireÂ - 53 PSI
3) Left rear duals Â Â Â - 74 PSI
4) Right rear duals - 72 PSI

The required tire pressures above were determined from the following Goodyear Tire website: www.goodyear.com/rv/pdf/rv_inflation.pdf

Also, the Bridgestone/Firestone website containing links to two different .pdf files containing detailed information of proper loading, weighing and tire inflation for your motorhome.

Those two links are as follows:

Firestone RV Tire14 page .pdf file:
http://www.trucktires.com/us_eng/librar ... ochure.pdf

Firestone RV Tire 6 page .pdf file: http://www.trucktires.com/us_eng/librar ... ghForm.pdf

BornFree_n_Now · Post by **BornFree_n_Now** » Mon Sep 19, 2005 12:42 am

Bill:

Every time this topic comes up, and someone kind, as yourself, posts the sources for inflation information (Firestone, in particular), I go and check out same, and continue to come to the point in the instructions that state:

â€œSame on both ends ~ Itâ€™s also important that you use the same inflation pressure on both ends of each axle. If axle end loads differ enough that the tables specify different inflation pressures for each end, the axle is out of balance enough that you should redistribute the load. If you canâ€™t do that, you must inflate the tires on both ends to the pressure required for the end with the heavier load.â€

whemme · Post by **whemme** » Mon Sep 19, 2005 1:39 am

Larry & Sharon,

Sorry everyone for the accidental double posting above!

I note that you have the same BF 26' RSB that I have. I have also seen the recommendations to use the same pressure in each tire on the same axle even though the side to side weight might be different. My experience with two Born Frees - one and earlier 1999 24' RB unit - is that they are generally heavier on the left side because of the fresh water tank is located on that side. I am not quit sure of the technical reason why the tire inflation pressures on both ends of a given axle must me the same. I can maybe see it on the rear axle to possibly prevent the differental needing to be too active when driving down a straight road. But I don't see the need on the fronts. As you see, I inflate one of my fronts to 55 psi, the other front to 60 psi and all rear duals to 75 psi.

I am also running a PressurePro tire monitoring system works very well. I also monitor the pressure in my toad's tires.

I think you will find that a careful front end alignment by a competent shop should take care of the inside tire edge wear. The twin I-beam front suspension on you Ford E-450 chassis left the factory with no means to adjust camber alignment. My alignment shop for both my 1999 and my current 2002 BF installed what they called adjustable camber bushings so that camber could be aligned properly.

Also, I was having trouble balancing the front Firestone LT225/75R-16E tires. I had them balanced twice with no improvement on a good Hunter balance machine and I was still getting vibration above 60 to 65 MPH. I finally went in a third time and explained to the technician that something was not getting done correctly and he then carefully went thru a complete balancing procedure putting different weights in different locations on both the inside and outside of the rims and also changing the mounting position of one tire on its rim.

Guess what, vibration problem solved on the third try!

bill crommett · Post by **bill crommett** » Mon Sep 19, 2005 12:21 pm

I have a philosophical approach that states that the tires should carry the maximum manufacturers pressure even though it may cause a rougher ride. In the advent of a slight overlaod condition due to temporary added cargo, if you deflate to a comfortable acceptable pressure, you will have an overloaded tire or pair. However the roughness of the ride will be, it will still be softer than a ride through the guard rails and into the ditch and beyond. So, if you follow the formula for inflation don't buy any souvenirs on the way.

BornFree_n_Now · Post by **BornFree_n_Now** » Mon Sep 19, 2005 4:11 pm

[quote="whemme"]Larry & Sharon,

"I think you will find that a careful front end alignment by a competent shop should take care of the inside tire edge wear. The twin I-beam front suspension on you Ford E-450 chassis left the factory with no means to adjust camber alignment. My alignment shop for both my 1999 and my current 2002 BF installed what they called adjustable camber bushings so that camber could be aligned properly."

Thank you for this information

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