Fifth Wheel Tire Pressure
I know there are several emails out there and I think I got it but never hurts to ask the group. I have a 30 ft Fifth Wheel with Carlisle Radial Trail RH Trailer Tires ST225 /75 R15 117N E1. The tire...
Forum Discussion
Depends on the loads that will be in your use on seperate tires.
This is not total weight minus pinload devided by number of tires on the ground.
Often there is a misbalance between tires on one axle of 48/52% or even more. Then also can be crossed between the axles , but this is not important for the pressure to use.
For that you only have to use pressure for the tire with most weight on it.
Then the tire side, an ST tire is calculated in its maximum load for more deflection allowed because of the lower speed of 65 m/h.
If it was set in the market as LT tire it would have about 15% lesser maximum load , because for higher speed ( LT mostly Q speedrated for 99m/h/160km/h) lesser deflection is allowed because of the more cycles the tire make a second.
Then if you would go from LT maxload for that tire sise and AT-presssure , you can even add a reserve of 18 % , to make the real weight 85% of weight you calculate the pressure for for 99m/h.
This is the upper border at wich still acceptable comfort and gripp, and gives lesser fuel consumption, and comfortable reserve for things like pressure loss in time , misreadings of pressure and weight scales, etc.
But calculating it like this will probably lead to a higher pressure then AT-pressure of yours 80 psi.
Tiremakers allow 10 psi higher, and in a document of Continental/semperit I found 1.4 times At pressure as advice when standing still and then 2 times maximum load allowed on tire.
Tires and valves can stand this higher pressure , rimms dont allow it always , its written on inside of rimms often , max pressure or maxload .
Once read that tires can stand a pressure of 2 to 3 times AT pressure ( yours 80 psi) . This would mean that if you would fill your tires at 1.4 times At pressure at freesing point of water, and temp inside tire rises to even boiling point of water, the pressure would rise to about 2 times AT- pressure , wich they can stand ( your tires 2x 80 psi= 160 psi)
So if you give more details of tires ( maxload ( 117 loadindex so 2830 lbs maxload),maxspeed ( 65m)and loadrange(E-load because of 80 psi) and of 5th wheeler ( number of axles and number of tire on the road and total weight and pinload percentage or weight), I will put it in my Traveltrailer calculator and give an extrasave advice.
reading back I see N speedrated for your tires wich is up to 81 m/h maxspeed , but because of ST it can be that maxload is given still for 65m/h, have to find out by comparing with other tires of same sises and loadrange.
Tire data so I already have, but only need 5th wheeler data.
This is not total weight minus pinload devided by number of tires on the ground.
Often there is a misbalance between tires on one axle of 48/52% or even more. Then also can be crossed between the axles , but this is not important for the pressure to use.
For that you only have to use pressure for the tire with most weight on it.
Then the tire side, an ST tire is calculated in its maximum load for more deflection allowed because of the lower speed of 65 m/h.
If it was set in the market as LT tire it would have about 15% lesser maximum load , because for higher speed ( LT mostly Q speedrated for 99m/h/160km/h) lesser deflection is allowed because of the more cycles the tire make a second.
Then if you would go from LT maxload for that tire sise and AT-presssure , you can even add a reserve of 18 % , to make the real weight 85% of weight you calculate the pressure for for 99m/h.
This is the upper border at wich still acceptable comfort and gripp, and gives lesser fuel consumption, and comfortable reserve for things like pressure loss in time , misreadings of pressure and weight scales, etc.
But calculating it like this will probably lead to a higher pressure then AT-pressure of yours 80 psi.
Tiremakers allow 10 psi higher, and in a document of Continental/semperit I found 1.4 times At pressure as advice when standing still and then 2 times maximum load allowed on tire.
Tires and valves can stand this higher pressure , rimms dont allow it always , its written on inside of rimms often , max pressure or maxload .
Once read that tires can stand a pressure of 2 to 3 times AT pressure ( yours 80 psi) . This would mean that if you would fill your tires at 1.4 times At pressure at freesing point of water, and temp inside tire rises to even boiling point of water, the pressure would rise to about 2 times AT- pressure , wich they can stand ( your tires 2x 80 psi= 160 psi)
So if you give more details of tires ( maxload ( 117 loadindex so 2830 lbs maxload),maxspeed ( 65m)and loadrange(E-load because of 80 psi) and of 5th wheeler ( number of axles and number of tire on the road and total weight and pinload percentage or weight), I will put it in my Traveltrailer calculator and give an extrasave advice.
reading back I see N speedrated for your tires wich is up to 81 m/h maxspeed , but because of ST it can be that maxload is given still for 65m/h, have to find out by comparing with other tires of same sises and loadrange.
Tire data so I already have, but only need 5th wheeler data.
