Tire Pressure

[ColonelJ]

What is a good tire pressure for 245/70r 19.5 tire on 2005 Terra, class A. Sidewall has 120 PSI Max, sound like very high? Hankook tires. Need recommendations.

Thanks in advance.

[dbates]

D Bates wrote:
If you want a complete answer to your question download & read THIS for Michelin tire's PDF file. It explains the proper way to weigh your RV and what pressures to use accordingly. I switched to Hankook last year and Hankook advised their tire pressures are the same as Michelin but they don't have a downloadable PDF.
Dave

I called USA Hankook as the dealer didn't know for sure.

Dave

[Sooner_Schooner]

I admit that I am fairly new to the Class A lifestyle so I am not an expert, we had a 5th wheel before, but I have put nearly 5000 miles on our coach. My 22.5 in tires specify max of 120 lbs, but I put 110 lbs in each tire since I feel very comfortable I am not too heavy. We travel with empty tanks except for a very little fresh water and I don't think we carry too much cargo. So unless you are a pack rat and carry tons of stuff, you could stay a little less than max pressure and probably be just fine.Our coach rides and drives just fine with the 110 lbs of pressure.

[tropical36]

wolfe10 wrote:
BEST answer: With the coach loaded the way you travel (with full fuel), weigh each wheel position and use the heavier wheel position to go to your tire manufacturer's Inflation table to determine the correct MINIMUM PSI. Perhaps add 5-10 PSI to that minimum.

Next best: Weight axles and go to the Inflation table. Add a little more for "fudge factor" to account for left/right imbalance.

Next best: Go with the pressures on your GVWR plaque (probably near driver's area) which is correct PSI if each axle is loaded to its maximum GAWR.

Worst (hopefully): What is on the sidewall of the tire.

Very good!
What so many seem to miss and especially with older coaches, along with not really wanting to take the time and do it right, is that the max psi rating on a modern tire's sidewall isn't necessarily the max psi rating of the wheel rim itself and many are limited to 90psi from my observation.

[GTN_and_Catz]

dbates wrote:
If you want a complete answer to your question download & read THIS for Michelin tire's PDF file. It explains the proper way to weigh your RV and what pressures to use accordingly. I switched to Hankook last year and Hankook advised their tire pressures are the same as Michelin but they don't have a downloadable PDF.
Dave

Dave - Do you know if that's Hankook's "official" stance or just your retailer's advice? I'm asking because I too switched to Hankook's, am very pleased with them but I'd like the "official" word to go by as well.
thanks - Gene

[dbates]

If you want a complete answer to your question download & read THIS for Michelin tire's PDF file. It explains the proper way to weigh your RV and what pressures to use accordingly. I switched to Hankook last year and Hankook advised their tire pressures are the same as Michelin but they don't have a downloadable PDF.

Dave

[Effy]

jadatis wrote:
I am able to calculate it with one of my made spreadsheets.
But also need weights on seperate wheels , determined as accurate as possible. In case of only GAWR/GVWR also try to give empty weight and the way you load it normally.
But there is not one pressure that is the right one.
For a sertain load there is a range in the pressure at wich the tires wont damage and no terrible bumping, Then keep to the highest pressure with no bumping and if in use it falls back to the lowest pressure with no damage, your tires are still save.

Further will copy text I use on many fora and saved , so dont have to write it all over again, but sometimes can be little off topic here.

So if you can give details of car and tires , I can calculate an advice pressure with some reserve for things like, pressure-loss in time, unequall loading R/L, incidental extra load, misreadings of pressure scales,and misyudging of weight, etc.

This is from tires next and can be read from sidewall:
Maximum load or loadindex.
Kind of tire to determine the AT-pressure/pressure needed for the maximum load up to maximum speed of tire, or if lower 160km/99m/h/reference-pressure, wich is not the maximum pressure of tire.
Maximum speed of tire, most given as letter ( Q=160km/99m/h,N=140km/86m/h fi)
If you have offroad or tires looking like that , with large profile blocs that cover a part of sidewall, also mention, they are allowed lesser deflection then a normal road tire, then the tire maker used to determine the maximum load (to my conclusion the case for the Bridgestone tires on Ford Explorer in the Ford/Firestone affaire).
If you cant find all of it give sises of tire and Loadkind, then I will google for it.

From car next and mostly can be found on same plate as the original pressure advices:
GAWR and GVWR ( Gross Axle/Vehicle Weight Rating)
But best would be to determine the real weights in your use on seperate tires or estimate it as acurate as possible, by weighing per wheel(pair) or axle.
Maximum speed , you dont go over for even a minute in your use, eventually different for different situations, for instance when towing or fully loaded.This apart from trafic regulations, if you drive faster then allowed give that speed. Nature punnisches with tire-failure, police only with a penalty.
Give all that and I will calculate and give a picture of one of my filled in spreadsheets in my answer.
If other then original tires, indead as is already answered other advice is needed, a stiffer tire ( fi C-load instead of P-tire) needs a higher pressure for the same load, or the other way around, has lower loadcapacity for the same pressure.
Greatings from a Dutch pigheaded self-declared tire-pressure-specialist.

huh? :h

[jadatis]

I am able to calculate it with one of my made spreadsheets.
But also need weights on seperate wheels , determined as accurate as possible. In case of only GAWR/GVWR also try to give empty weight and the way you load it normally.
But there is not one pressure that is the right one.
For a sertain load there is a range in the pressure at wich the tires wont damage and no terrible bumping, Then keep to the highest pressure with no bumping and if in use it falls back to the lowest pressure with no damage, your tires are still save.

Further will copy text I use on many fora and saved , so dont have to write it all over again, but sometimes can be little off topic here.

So if you can give details of car and tires , I can calculate an advice pressure with some reserve for things like, pressure-loss in time, unequall loading R/L, incidental extra load, misreadings of pressure scales,and misyudging of weight, etc.

This is from tires next and can be read from sidewall:
Maximum load or loadindex.
Kind of tire to determine the AT-pressure/pressure needed for the maximum load up to maximum speed of tire, or if lower 160km/99m/h/reference-pressure, wich is not the maximum pressure of tire.
Maximum speed of tire, most given as letter ( Q=160km/99m/h,N=140km/86m/h fi)
If you have offroad or tires looking like that , with large profile blocs that cover a part of sidewall, also mention, they are allowed lesser deflection then a normal road tire, then the tire maker used to determine the maximum load (to my conclusion the case for the Bridgestone tires on Ford Explorer in the Ford/Firestone affaire).
If you cant find all of it give sises of tire and Loadkind, then I will google for it.

From car next and mostly can be found on same plate as the original pressure advices:
GAWR and GVWR ( Gross Axle/Vehicle Weight Rating)
But best would be to determine the real weights in your use on seperate tires or estimate it as acurate as possible, by weighing per wheel(pair) or axle.
Maximum speed , you dont go over for even a minute in your use, eventually different for different situations, for instance when towing or fully loaded.This apart from trafic regulations, if you drive faster then allowed give that speed. Nature punnisches with tire-failure, police only with a penalty.
Give all that and I will calculate and give a picture of one of my filled in spreadsheets in my answer.
If other then original tires, indead as is already answered other advice is needed, a stiffer tire ( fi C-load instead of P-tire) needs a higher pressure for the same load, or the other way around, has lower loadcapacity for the same pressure.
Greatings from a Dutch pigheaded self-declared tire-pressure-specialist.

[Goldencrazy]

My guess is you are going to pretty close to 85psi as that is typical in that range but check your vehicle and weigh.

[exioum]

Ask yourself, When your driving your car, suv or 12 passenger van on a trip do you adjust you tire psi if there is only two passengers? Do OTR busses change their psi if they only have 15 passengers instead of 40 or what ever their cap is? My suggestion is to follow the psi settings posted for your unit...
This does not mean not to check for proper weight distribution....

[Effy]

darsben wrote:
Since you probably will not weigh the rig the answer is the Maximum pressure on sidewall.

you forgot - and it will ride like your wheels are made of rocks.

[darsben]

Since you probably will not weigh the rig the answer is the Maximum pressure on sidewall.
Inflating to max = increased tire wear but RV tires usually age out before they wear out.
Under-inflation = Sudden rapid loss of inflation otherwise known as a blowout.
You make the call

[lanerd]

What Brett said.

FWIW, there are probably "daily" posts on this subject. It would probably be in your best interest to check some of them out by doing a search on the subject.

Ron

[wolfe10]

BEST answer: With the coach loaded the way you travel (with full fuel), weigh each wheel position and use the heavier wheel position to go to your tire manufacturer's Inflation table to determine the correct MINIMUM PSI. Perhaps add 5-10 PSI to that minimum.

Next best: Weight axles and go to the Inflation table. Add a little more for "fudge factor" to account for left/right imbalance.

Next best: Go with the pressures on your GVWR plaque (probably near driver's area) which is correct PSI if each axle is loaded to its maximum GAWR.

Worst (hopefully): What is on the sidewall of the tire.

[Effy]

Standard answer; load your coach for travel, including water, weigh your MH by 4 corners or at least by axle and go by the tire manufacturer's chart based on the weight per axle. That is the only way to get an accurate psi.