Community Forums

C Driver · 08-01-2005, 06:02 AM

Ah, a quandry .... Ford sticker says 80psi on the rear dually .... right next to it is a sticker from the manufacturer saying 65psi on the rear ... btw both say 65 on the front and they had 80 when we bought it ..... rear weight is 9450, which 'seems' to fall within the 'E' range tire pressure setting of 65 psi, but, well gee Ford says 80 .... hmmm!

C Driver · 08-01-2005, 06:02 AM

Ah, a quandry .... Ford sticker says 80psi on the rear dually .... right next to it is a sticker from the manufacturer saying 65psi on the rear ... btw both say 65 on the front and they had 80 when we bought it ..... rear weight is 9450, which 'seems' to fall within the 'E' range tire pressure setting of 65 psi, but, well gee Ford says 80 .... hmmm!

knute · 08-01-2005, 07:54 AM

Whats on the tire sidewall??

I'm no tire expert, but I think I would tend to believe the tire manufacturer.

Ford doesn't have a great reputation regarding tire pressure reccomendations. Remember the Ford SUV rollovers from blowouts on 22 psi tires. Under-inflated by 10-15 psi.

"007" · 08-01-2005, 09:33 AM

Are you talking about tire Mfg or coach Mfg

If its your tire Mfg GY, Mich, go by their psi on their weight tables after you have your MH weight. Cat scales cost about $8.

"007"

C Driver · 08-01-2005, 01:04 PM

For a clarification : the one sticker is from Ford, the chassis manufacturer stating 80 psi the other is from the coach manufacturer stating 65psi
The unit weighs 9450 on the rear and 3725 on the front, loaded with tanks about half full. The M tire inflation chart shows 65psi will support around 2600 pounds, so a dually rear system should be around 10,800 capacity, therefore I see no reason to run them at 80 psi
Also I would assume that I would get a better, more stable ride with them at 65psi

Gary RVRoamer · 08-01-2005, 02:43 PM

Whoa! Dual tire carrying capacity is always less than single tires - the weight tables for the tire will show that. It is usually shown on the sidewall a well, if the tire is rtaed for use as a dualie. That means duals generally need to be inflated more than the front tires would be for the same load carrying capacity.

The inflation shown on the sidewall is the inflation needed for the tires max load capacity. It is NOT the tire manufacturers "recommended" inflation.

I suspect the Ford chassis recommendation is also for the chassis max load, i.e. with the rear axle loaded to its GAWR. Ford doesn't know how the chassis wil be loaded when they sell it, so they sticker it for max load. The coach builder, however, knows the weight of the body built on the chassis, the weight distribution and the tank capacities and can make some reasonable estimates of total loading. Obviously they fell your weight will always be substantially under the max for the chassis.

Start with the coach builder's recommendation and then use the actual weight of your particular rig, when loaded as you use it, to determine the final pressure, using the tire manufacturers load tables. It sounds as though around 65-70 psi rear will be fine. Front will be even less. Err on the side of higher inflation rather than low, but no more than 10 psi above the inflation table recommendation.

Stan Birch · 08-06-2005, 03:46 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RV Roamer:
Err on the side of higher inflation rather than low, but no more than 10 psi above the inflation table recommendation. </div></BLOCKQUOTE>
Good rule of thumb. I find that an extra 10 lbs in the front tires make a dramatic improvement in handling.

Gus Weber · 08-12-2005, 09:49 AM

Note also that the tire inflation tables are for a max 65 MPH. To go faster, add 10 psi to each tire. Above 75 MPH, manufacturers tell you how much to decrease the weight on the tires.

Be safe

Gus Weber

C Driver · 08-18-2005, 06:38 AM

Spent some time over the last couple of days playing with tire pressure .... found that with 65psi in the front the handling was actually worse than with 80psi in them .... Did not notice a lot of difference with the rear tires set at 65, 70 or 80 although the overall ride was a little better when they were at 65 and 70 ...
Just curious that the steering should be better with more pressure in them .... so after a lot of playing I think I am going to leave them all at 70 psi which is above the weight/pressure tables but below the 80 max pressure for these 'E' rated tires ...