Tire Pressure from chart vs door sticker

[Mark S]

My Seneca came with 110 psi in each tire and that is what the door sticker recommends. The ride felt like it wandered a bit. I went to the Cat scales and had my RV weighed:

Front axle= 8,400 pounds
Rear axle = 14,300 pounds

According to the Michelin inflation chart for 275/80 R22.5 G tires, at 85 psi with a single wheel the max load per axle is 10,310 lbs and on a dual the max load is 18,760 lbs. This means to me that 85 psi the front axle is about 2,000 pounds under the max load and the rear is 4,000 pounds under.

So if I am happier with the ride and handling at 85 psi than at 110 psi, is there any reason to run the 110 psi? I believe I have a healthy safety margin with those numbers. Am I seeing this correctly?

I am driving to Orlando the morning, about 200 miles, so i should get a good feel for the ride.

Thanks, Mark

[Crossingover]

Originally Posted by Mark S

So if I am happier with the ride and handling at 85 psi than at 110 psi, is there any reason to run the 110 psi? I believe I have a healthy safety margin with those numbers. Am I seeing this correctly?

Partly. For peace of mind at the expense of being over-inflated for the actual axle weights, we keep ours near 110 and never drift south of 95. One of those 'set it and forget it' safety items of utmost importance. We didn't buy a truck with the illusion to achieve a comfy ride by airing down the tires. If yours is wandering (ours does not and runs true under all conditions), I would include a suspension/alignment check during your visit to the Orlando facility.

[Mark S]

There is also the thought that if overinflated for the weight there is less tire surface on the road. I remember hearing of the chalk test where you draw a chalk line on the thread and roll over it to determine how much tire touches the surface or something like that as anyway to determine proper inflation. For this trip I will try the Michelin PSI-load chart.

[SloPoke]

Originally Posted by Mark S

My Seneca came with 110 psi in each tire and that is what the door sticker recommends. The ride felt like it wandered a bit. I went to the Cat scales and had my RV weighed:

Front axle= 8,400 pounds
Rear axle = 14,300 pounds

According to the Michelin inflation chart for 275/80 R22.5 G tires, at 85 psi with a single wheel the max load per axle is 10,310 lbs and on a dual the max load is 18,760 lbs. This means to me that 85 psi the front axle is about 2,000 pounds under the max load and the rear is 4,000 pounds under.

So if I am happier with the ride and handling at 85 psi than at 110 psi, is there any reason to run the 110 psi? I believe I have a healthy safety margin with those numbers. Am I seeing this correctly?

I am driving to Orlando the morning, about 200 miles, so i should get a good feel for the ride.

Thanks, Mark

Every time we pick up our Seneca from Freightliner after they perform scheduled maintenance, they air the tires up to 110psi. It is WHAT they do as part of the maintenance - Just like a Tire Dealer will inflate a tire to the FULL pressure, even if it is not needed.

On the road home... the ride is different, it wanders more than it did with the tires at "Michelin's recommended pressure" and you can feel every little detail in the pavement.

Our XZE2's dont need a full 110psi since we are not ever going to run 12k on our front axle.. We find a pressure that is within the specifications by the tire manufacturer and stay well within the range they specify... We also have a TPMS system so everyone can know exactly what your pressures AND temperatures are while you are travelling with your family down the road.

So... if you ask me what we run as pressure??? it depends on what we are hauling, what we expect to weigh, what time of they year it is (cold/hot). But the only time we run at full (110) pressure is on the way home from Freightliner.

[WaltW]

Go with the Michelin RV tire recommendations (not truck or car). Its provides better ride, handling and safety. The overinflated tire will wear more in the center. Also never run the tires at less than 75% of rated max. This will cause the sidewalls to flex too much and cause premature failure.

When using the tables add 10% to allow for left to right weight difference if you don't weigh 4 corners. If you weigh 4 corners set at the higher pressure keeping both sides the same. Tires pressures are always set at cold temps. The mfger already took the heat build-up from driving into consideration.

[Mark S]

Thanks Walt. Good information.

[Grumpy]

Originally Posted by Mark S

So if I am happier with the ride and handling at 85 psi than at 110 psi, is there any reason to run the 110 psi? I believe I have a healthy safety margin with those numbers. Am I seeing this correctly?

Thanks, Mark

Absolutely, no reason to run max. A call/ e mail to MICHELIN and they will tell you the same thing. Every body I know who followed the pressure chart have had no issues and better handling.

[mike837go]

X2 on getting the alignment checked/adjusted.

Generally, if the tires are equally inflated and loaded fairly evenly, the vehicle will track straight.

Wandering or having to activly fight to stay in lane usually means small problems that should be dealt with before they become serious issues.

[richard66]

I run 95 psi in all tires and very satisfied with the ride, tire wear and the how it handles. 2014 Seneca FK

[javamon]

Hi Mark,

Just got back from a trip to MD so I've been off the radar for several weeks. The trip was 980 miles each way so I definitely had a chance to observe tire pressure. Going up I had all tires at 100 psi cold. Once the tires heated-up the ride was still much too harsh. The steering wheel feedback when I would hit a bump was horrible. For the trip back I knocked the pressure down to 90, with much improvement. I am definitely going to go down to 85 for our summer trip out west. Overall though, I was very impressed with the ride and handling of the M2. The first day was a 700 mile day and I was surprised how well I held up. It was also my experience that the M2 seemed to wander when I was running 110. That definitely went away when I reduced pressure down to 90.

[Mark S]

Welcome back Javamon. Glad you had a good trip.

85 psi seemed to work pretty well for me. After weighing mine I used the Michelin chart for the weight on my axles plus a safety factor I just made up. I could actually run less according tho the chart but decided to play it safe.