Tire PSI for H3 Adventure Package ?
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Joined: Jul 2009
Posts: 30
No, you can't use the tire sidewall pressures... tires of the same size can be used on a wide range of vehicles that can have substantial differences in weight.
The tire only lists the maximum limits; both for pressure and load range... there is no way a tire can tell you what to use for your specific vehicle. You wouldn't use the same pressure for a 5000lb vehicle as you would a 1000lb vehicle would you?
It is the same concept as an exercise ball, if you read the instructions they will indicate for a skinny 100lb girl to use a lower pressure than a large 250lb guy.
Typically you should always follow the sidewall pressure on the door jam. When changing tire size to something wider you can add even just a couple of pounds of pressure to change the tire contact patch back to stock.
The tire only lists the maximum limits; both for pressure and load range... there is no way a tire can tell you what to use for your specific vehicle. You wouldn't use the same pressure for a 5000lb vehicle as you would a 1000lb vehicle would you?
It is the same concept as an exercise ball, if you read the instructions they will indicate for a skinny 100lb girl to use a lower pressure than a large 250lb guy.
Typically you should always follow the sidewall pressure on the door jam. When changing tire size to something wider you can add even just a couple of pounds of pressure to change the tire contact patch back to stock.
Thank You !
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Joined: Jul 2007
Posts: 13,056
From: Boat Town USA MI
No, you can't use the tire sidewall pressures... tires of the same size can be used on a wide range of vehicles that can have substantial differences in weight.
The tire only lists the maximum limits; both for pressure and load range... there is no way a tire can tell you what to use for your specific vehicle. You wouldn't use the same pressure for a 5000lb vehicle as you would a 1000lb vehicle would you?
It is the same concept as an exercise ball, if you read the instructions they will indicate for a skinny 100lb girl to use a lower pressure than a large 250lb guy.
Typically you should always follow the sidewall pressure on the door jam. When changing tire size to something wider you can add even just a couple of pounds of pressure to change the tire contact patch back to stock.
The tire only lists the maximum limits; both for pressure and load range... there is no way a tire can tell you what to use for your specific vehicle. You wouldn't use the same pressure for a 5000lb vehicle as you would a 1000lb vehicle would you?
It is the same concept as an exercise ball, if you read the instructions they will indicate for a skinny 100lb girl to use a lower pressure than a large 250lb guy.
Typically you should always follow the sidewall pressure on the door jam. When changing tire size to something wider you can add even just a couple of pounds of pressure to change the tire contact patch back to stock.
The load range of the tire to put on vehicle is determined by the vehicle weight, so unless you have the wrong load range tires for your truck (in which case you have a world of more troubles than worrying about what PSI to use) the sidewall pressure is what the tire engineers determined to be safe. So, there ain't no way your gonna have the same tire for use on a 1000# vehicle and a 5000# vehicle.
Senior Member
Joined: Nov 2009
Posts: 249
^^ Agreed, that is why the max PSI is written on the tire, so you don't put more than the maximum safe air pressure in the tire... if your door jam tire pressure exceeds the max tire pressure then the tire is no good for the vehicle.
Tire pressures are set by the vehicle manufacturer; there is a lot of engineering that goes into determining that pressure. Many tires that fit Jeeps will fit Hummers, why would you use the max sidewall pressure written on the tire?
As a side note I also do Autocrossing as a hobby sport with my other car; to determine the best tire pressure for this kind of racing you can either use a heat gun or use something like a dab of shoe polish on the sidewall to determine how far the tire is rolling over on corners. Typically the optimum pressure for this kind of racing is about 6-10psi over the door jam... it can vary a bit depending on what kind of tire material and how it handles heat.... but typically it is almost always in that range. But all variations aside there is one critical thing about running these "optimal" autocross pressures, while your hard corner handling ability goes up... your braking distance also increases drastically. These are not the best operating pressure for the car, in fact I would go as far as to say they are down right dangerous outside of a track.
The best pressure for your car is usually exactly what is written on the door jam. That pressure will give you an optimum contact patch for handling, braking and comfort. The exception ot the rule is when you change profile or width, you make adjustments... usually you only need to be a couple of PSI different from the manufacturer recommended pressures.
TireRack actually has a nice article on it:
http://www.tirerack.com/tires/tirete...e.jsp?techid=8
Tire pressures are set by the vehicle manufacturer; there is a lot of engineering that goes into determining that pressure. Many tires that fit Jeeps will fit Hummers, why would you use the max sidewall pressure written on the tire?
As a side note I also do Autocrossing as a hobby sport with my other car; to determine the best tire pressure for this kind of racing you can either use a heat gun or use something like a dab of shoe polish on the sidewall to determine how far the tire is rolling over on corners. Typically the optimum pressure for this kind of racing is about 6-10psi over the door jam... it can vary a bit depending on what kind of tire material and how it handles heat.... but typically it is almost always in that range. But all variations aside there is one critical thing about running these "optimal" autocross pressures, while your hard corner handling ability goes up... your braking distance also increases drastically. These are not the best operating pressure for the car, in fact I would go as far as to say they are down right dangerous outside of a track.
The best pressure for your car is usually exactly what is written on the door jam. That pressure will give you an optimum contact patch for handling, braking and comfort. The exception ot the rule is when you change profile or width, you make adjustments... usually you only need to be a couple of PSI different from the manufacturer recommended pressures.
TireRack actually has a nice article on it:
http://www.tirerack.com/tires/tirete...e.jsp?techid=8
TIRERACK TIRETECH
........The pounds per square inch (psi) pressure number branded on the tire's sidewall identifies the maximum cold inflation pressure that specific tire is rated to hold. However, the tire's maximum pressure is not necessarily the correct pressure for every vehicle upon which the tire can be used (almost all vehicle manufacturers' recommended tire inflation pressures are less than the tires' maximum pressure).
Therefore when checking and adjusting tire inflation pressures, the "right" inflation pressures are those provided by the vehicle manufacturer, not the "maximum" inflation pressure branded on the tire's sidewall. The vehicle manufacturer's pressure recommendation can be found on the vehicle's tire information placard label, as well as in the vehicle owner's manual......
........The pounds per square inch (psi) pressure number branded on the tire's sidewall identifies the maximum cold inflation pressure that specific tire is rated to hold. However, the tire's maximum pressure is not necessarily the correct pressure for every vehicle upon which the tire can be used (almost all vehicle manufacturers' recommended tire inflation pressures are less than the tires' maximum pressure).
Therefore when checking and adjusting tire inflation pressures, the "right" inflation pressures are those provided by the vehicle manufacturer, not the "maximum" inflation pressure branded on the tire's sidewall. The vehicle manufacturer's pressure recommendation can be found on the vehicle's tire information placard label, as well as in the vehicle owner's manual......
Last edited by Sugarphreak; Apr 23, 2010 at 03:46 PM.
Senior Member
Joined: Jul 2005
Posts: 108
From: Moab
^^ Agreed, that is why the max PSI is written on the tire, so you don't put more than the maximum safe air pressure in the tire... if your door jam tire pressure exceeds the max tire pressure then the tire is no good for the vehicle.
With the H3, the factory tires are Load Range C, which is 50 psi.
Tire pressures are set by the vehicle manufacturer; there is a lot of engineering that goes into determining that pressure. Many tires that fit Jeeps will fit Hummers, why would you use the max sidewall pressure written on the tire?
You sure are right. GM has an extensive tire testing lab in Milford and that is also spread out to the other proving grounds in AZ and Northern Canada for testing of tires in extreme hot and cold conditions. And it is not a one-day process, it can take months and massive amounts of data before a tire and the recommended pressure readings are determined for all models.
As a side note I also do Autocrossing as a hobby sport with my other car; to determine the best tire pressure for this kind of racing you can either use a heat gun or use something like a dab of shoe polish on the sidewall to determine how far the tire is rolling over on corners. Typically the optimum pressure for this kind of racing is about 6-10psi over the door jam... it can vary a bit depending on what kind of tire material and how it handles heat.... but typically it is almost always in that range. But all variations aside there is one critical thing about running these "optimal" autocross pressures, while your hard corner handling ability goes up... your braking distance also increases drastically. These are not the best operating pressure for the car, in fact I would go as far as to say they are down right dangerous outside of a track.
Never autocrossed, but know many who did and the do run max pressures. And I agree, max pressures on the highway can be dangerous and should only be used IF there is a need, and on the H3, there will never be a need.
The best pressure for your car is usually exactly what is written on the door jam. That pressure will give you an optimum contact patch for safety handling, braking and comfort. The exception ot the rule is when you change profile or width, you make adjustments... usually you only need to be a couple of PSI different from the manufacturer recommended pressures.
Very true, except the first word in the second sentence needs to be SAFETY; at least from GM's tire group.
With the H3, the factory tires are Load Range C, which is 50 psi.
Tire pressures are set by the vehicle manufacturer; there is a lot of engineering that goes into determining that pressure. Many tires that fit Jeeps will fit Hummers, why would you use the max sidewall pressure written on the tire?
You sure are right. GM has an extensive tire testing lab in Milford and that is also spread out to the other proving grounds in AZ and Northern Canada for testing of tires in extreme hot and cold conditions. And it is not a one-day process, it can take months and massive amounts of data before a tire and the recommended pressure readings are determined for all models.
As a side note I also do Autocrossing as a hobby sport with my other car; to determine the best tire pressure for this kind of racing you can either use a heat gun or use something like a dab of shoe polish on the sidewall to determine how far the tire is rolling over on corners. Typically the optimum pressure for this kind of racing is about 6-10psi over the door jam... it can vary a bit depending on what kind of tire material and how it handles heat.... but typically it is almost always in that range. But all variations aside there is one critical thing about running these "optimal" autocross pressures, while your hard corner handling ability goes up... your braking distance also increases drastically. These are not the best operating pressure for the car, in fact I would go as far as to say they are down right dangerous outside of a track.
Never autocrossed, but know many who did and the do run max pressures. And I agree, max pressures on the highway can be dangerous and should only be used IF there is a need, and on the H3, there will never be a need.
The best pressure for your car is usually exactly what is written on the door jam. That pressure will give you an optimum contact patch for safety handling, braking and comfort. The exception ot the rule is when you change profile or width, you make adjustments... usually you only need to be a couple of PSI different from the manufacturer recommended pressures.
Very true, except the first word in the second sentence needs to be SAFETY; at least from GM's tire group.
As for a statment, "So, there ain't no way your gonna have the same tire for use on a 1000# vehicle and a 5000# vehicle..." Well, yes you can.
Many people upgrade their tires to a higher load range/tire index. I did on my H3 and I bet you did to when you went to the Mickey Thompsons. I believe they are D and have a higher load index than the stock Bridgestones which are C. But the factory will go with the smallest load range/load index that can meet all the requirements shown above; especially safety.
And with the comment about Ford. You are correct. Firestone/Bridgestone noted to Ford that the recommended pressure listed in their owner's manual and the tire placard was incorrect. Ford wanted their owners to have a softer ride, so they went with 5 psi less. Then add that 5 psi under the tire manufacturers recommendations, to the fact that close to 80 percent (from a NHTSA study taken a few years ago) of vehicle owners have no idea how to check their tire pressures ( or allow the jerk in the oil change shop to check them and remove pressure from a hot tire to match the placard), then overload the vehicle (no one pays attention to GVWR ratings either), then run in southern TX on a nice 100 degree day, and you have an accident looking for a place to happen at 75 mph.
Last edited by f5fstop; Jul 31, 2011 at 12:53 PM.
Junior Member
Joined: May 2011
Posts: 9
From: SE Wisconsin
1306lbs. payload divided by 265lbs = 4.92. Lose a few lbs and 5 of you can go. LOL
Junior Member
Joined: May 2011
Posts: 9
From: SE Wisconsin
To be specific that payload is for h3 lux. payload for h3x is 1280lbs and an alpha is 1118lbs.