Tire Pressures

[BobC]

I weighed my coach yesterday and it shows:

Steer Axle..........7020

Drive Axle..........11960

Gross Weight......18980

I have Goodyear G670 245/70/19.5 tires. 2016 Thor Hurricane 35C

The Goodyear Tire Inflation Table shows the recommended tire pressures are:

Steer Axle @ 7020 divided by 2= 3510#.....80# Lowest weight shown is 3640#

Drive Axle @ 11960 divided by 2= 5980#...110# The highest weight shown on the chart is 4410#

Are these pressures correct or am I doing something wrong in my calculations?
I have been running 95#s on all tires without any problems before I finally got it weighed. Four corner scales are hard to find in Florida so I had to use axle weights.

I know tire pressures have been beaten to death on the forums but I appreciate any "constructive" input you have.

TIA Bob

[Grumpy Grampa]

How does your RV tire size and tire pressure compare to what is posted on your coach?

[The Gritz Carlton]

I'm with Grumpy...go by what's posted in the door jam. That's more specific to your actual chassis than a generic chart.

[cpmath]

I have always went by the sticker on the door jamb, driver's side. Never had a problem so far with a tire. 2016 Thor Freedom Elite 22.

[BobC]

Originally Posted by Grumpy Grampa

How does your RV tire size and tire pressure compare to what is posted on your coach?

The sticker in the coach says 95 all the way around, which I have been using.

My last RV, not a Thor, showed 65 pounds on the sticker and after the second rear-tire blow-out I found out the sticker should have read 95. Newbie at the time.

Thanks, Bob

[Rclbud]

drive axle 11960/4 (not 2) there are four tires. Right ?

[BobC]

Originally Posted by Rclbud

drive axle 11960/4 (not 2) there are four tires. Right ?

If I divide the rear axle by four it would put the tire pressures at 65 or less.

The inflation chart for Goodyear shows single or dual pressures by axle I think, not the corner weights.

[Rclbud]

I just did this exercise and I think you have to divide the axle weight by number of tires...

Being single or dual tires on an axle modifies the numbers slightly for redundancy is how it looked to me.

Otherwise none of our rear tires would be within the range.. we would all be at 150 lbs of pressure.

[16ACE27]

Originally Posted by BobC

If I divide the rear axle by four it would put the tire pressures at 65 or less.

The inflation chart for Goodyear shows single or dual pressures by axle I think, not the corner weights.

No, Bud is correct: The chart says "TIRE LOAD LIMITS (LBS) AT VARIOUS COLD INFLATION PRESSURES" - So 80 PSI for the rear as well.

The 95 PSI sticker is at GVWR for the chassis which I believe is 22K for your coach.

[Lt Keefer]

Another tire pressure thread with no consensus, who woulda thunk it? I just surprised nobody has mentioned the supposed benefits of a TPMS system yet!

[ducksface]

Here's a thought to compliment the thought above:
The sun on the sunny side of your RV changes tire pressure by 10+lbs dependant on the season. As you change direction or time of day, your pressures go all over the place. It's the law.

Chasing tire pressure is an obsession.
Don't let the obsession ruin your trip due to brain strain.
Get close, get comfortable, call it good.

Think about what you chase.
Think about how the real world works.
Theory and laboratory tests create real world parameters, not real world specifics.
(Tpms is a great thing to give you EMERGENCY NOTICES. It is not a good thing to obsess and stare at)

[Bob Denman]

Was your last RV a Tiffin?
We just received a new tire inflation sticker for ours: 80 psi; instead of 60...

[Chateau_Nomad]

Had 75psi in class C RV tires and 31 in the toad Wrangler tires... according to my TPMS on Saturday morning. Usually have 80 in the RV and 33 in Jeep. Close enough.

Drove 250+ miles Saturday in the rain... about 60 degrees. Pressure increased in every tire 3 to 5 psi. On hot days it's more like 10 psi.

That's all the info I need...

[Travelin' Texans]

These inflation threads never end & never will regardless if it's motorhomes or towables. Folks obsess over a few pounds up or down, WHY? The recommended pressures are posted right on the rv in black & white, how much simpler can it be? Use those, 1 less thing to worry about!!
We're talking motorhomes here & I'm guessing the majority are on a Ford chassis, from experience those, trucks or motorhomes, will NEVER ride like a Lincoln nor handle like a sports car regardless of tire pressures, it's a Ford truck with a house on it.

[Jimbo56]

Originally Posted by BobC

I weighed my coach yesterday and it shows:

Steer Axle..........7020

Drive Axle..........11960

Gross Weight......18980

I have Goodyear G670 245/70/19.5 tires. 2016 Thor Hurricane 35C

The Goodyear Tire Inflation Table shows the recommended tire pressures are:

Steer Axle @ 7020 divided by 2= 3510#.....80# Lowest weight shown is 3640#

Drive Axle @ 11960 divided by 2= 5980#...110# The highest weight shown on the chart is 4410#

Are these pressures correct or am I doing something wrong in my calculations?
I have been running 95#s on all tires without any problems before I finally got it weighed. Four corner scales are hard to find in Florida so I had to use axle weights.

I know tire pressures have been beaten to death on the forums but I appreciate any "constructive" input you have.

TIA Bob

Divide the drive axle by 4

[gmc]

Some things never change... including threads about tire pressure... lol
But the summary:

• The placard in the RV gives tire pressures at max weight.. safe to use (assuming the sticker is right )
• The tire manufacturer charts give the pressure based on weight loading... (yes - divide the axle weight by the number of tires on the axle)
• If using actual weights, be sure your rig was loaded as you travel when weighed... tanks, cargo, people... I had a significant weight difference when configured for weekend/week trips vs a 3 month snowbird trip (flirting with max chassis weight then)...

Set your pressures somewhere between these too (personal preference as to where) and you should be fine...


I does use a TPMS to hopefully detect a major issue before it goes boom... monitoring both the coach and toad tires - may surprise you how much pressures change... I had to adjust 'target' settings to avoid false alarms for temp... especially on inner rear tires. Once set - forget it unless the alarm goes off.

[ducksface]

I think tire pressure/load threads have changed a lot.

The years prior we had people who actually took their mattress out of their motorhome and carried it in the towed because the four-corner 1/2lbpsi guys scared them so bad.

In years past I was accused of blasphemy for suggesting that some wog junior engineer cube-dweller had to put SOMETHING on paper so he took a shot.
And
That the word seller in that rag which prints 300 word articles wrote about pineapples last month, ANOTHER subject she knows no more about than the towing limits she writes about in this months advertising gazzette.

Now in this thread almost everyone is saying to get close and enjoy life.

I think we're evolving from
6 volt batteries are real-world measurably better
Gvw is the very word of god
Reverse osmosis water kills you by denial of minerals
Towing capacity is measured in weight of feather pillows.
3,000 mile oil changes
Tire pressure is measured in a/10th psi and is an absolute and physics is a lie.
Fuel mileage is the ultimate consideration, floor plan be damned, I'll sleep on a triple folded hidabed to save.3mpg

to where we are now in this conversation:
Get close, get on the road.

[jadatis]

Originally Posted by BobC

I weighed my coach yesterday and it shows:

Steer Axle..........7020

Drive Axle..........11960

Gross Weight......18980

I have Goodyear G670 245/70/19.5 tires. 2016 Thor Hurricane 35C

The Goodyear Tire Inflation Table shows the recommended tire pressures are:

Steer Axle @ 7020 divided by 2= 3510#.....80# Lowest weight shown is 3640#

Drive Axle @ 11960 divided by 2= 5980#...110# The highest weight shown on the chart is 4410#

Are these pressures correct or am I doing something wrong in my calculations?
I have been running 95#s on all tires without any problems before I finally got it weighed. Four corner scales are hard to find in Florida so I had to use axle weights.

I know tire pressures have been beaten to death on the forums but I appreciate any "constructive" input you have.

TIA Bob

Filled it in in my made calculator i wich first 10% added to the axleweight, for reserve, and then calculates with a safer formula then the official european.

Had to switch browser to get my story here,
Your tires have probably speedcode L ( 75mph max)
Maximum N ( 87mph max) , but try to find that.
I determined that if calculated for 99mph ( Q speedrate or higher) and my 10% added, it will give max reserve with acceptable comfort and gripp, so give your speedcode and I can calculate an even higher pressure.

[MLP]

When I first got my Palazzo I had the axle weight. I added ten psi to the load pressure chart minimum required pressure. When I was able to get the four corner weights, I was just 5psi over the required psi do to one side being heaver than the other. I like to keep ten psi over the minimum required psi. The ride is good and so is the handling. When it gets cold, I do not have to adjust the tire pressure.

[dkoldman]

So I have the exact same tires G670 245/70R/19.5 what should I do?

My coach has never been on a scale, I decided to buy another tank of gas versus paying $400 for a TPMS; so no TMPS, I don't have a Viair, my coach was delivered at 82 psi on all 6 tires, I was told by Dealer during PDI I should always maintain 82 psi, then he told me not to worry to write that down because it was on the yellow sticker, then I confirmed with the RV Mfg how to read the yellow sticker and how they calculated the yellow sticker, I was told to emphatically to ensure tires were filled to yellow sticker (82psi Cold inflation).

All the same I came under fire from some because I did not get a weigh. So I did the math, based on GVWR if I ever hit that limit (23k) the distributed weight on my tires would be 85 psi each. Of course my actual calculated weight with max loads and full tanks is about 17.5k, so I decided to see what Goodyear says about my tires and my take away...

1. My tires (made after 2006) should NEVER EVER be less than 80 psi ( no matter how light)
2. If I have actual scale weigh on my axles that would actually warrant a tire pressure over 85 psi; then by extrapolation, my coach would be overweight per the design of RV Mfg & Ford Engineering.