1991 Chevrolet K1500. Original be tires were 225/75/16. Placard says 45 PSI. Currently running 245/75/16 tires. What should my PSI be?
How much PSI?
- Thread starter otis24
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LTs? Towing or carrying weight in the bed?
Go by the door jam imo. 225 to 245 isnt that big of difference.
Seems pretty high if the bed is empty
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
Originally Posted By: ammolab
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
Yeah, it's the other way around. The car maker knows the suspension and weight setup of the car. The tire maker has no idea. All they can do is specify a max. Go by whatever is on the door jam of the car. If it was up to the tire maker, you wouldn't even need a sticker, yet every car has one.
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
Yeah, it's the other way around. The car maker knows the suspension and weight setup of the car. The tire maker has no idea. All they can do is specify a max. Go by whatever is on the door jam of the car. If it was up to the tire maker, you wouldn't even need a sticker, yet every car has one.
Originally Posted By: Wolf359
Originally Posted By: ammolab
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
Yeah, it's the other way around. The car maker knows the suspension and weight setup of the car. The tire maker has no idea. All they can do is specify a max. Go by whatever is on the door jam of the car. If it was up to the tire maker, you wouldn't even need a sticker, yet every car has one.
+1
Originally Posted By: ammolab
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
Yeah, it's the other way around. The car maker knows the suspension and weight setup of the car. The tire maker has no idea. All they can do is specify a max. Go by whatever is on the door jam of the car. If it was up to the tire maker, you wouldn't even need a sticker, yet every car has one.
+1
gathermewool
Site Donor 2025
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
Why would you post in all caps with bad gouge? Scary people, those who are 100% confident and not at all right...
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
Why would you post in all caps with bad gouge? Scary people, those who are 100% confident and not at all right...
Sorry MR expert. Maybe they can change the name of this sight to yours?,,
Max of 45 for the tire, anymore and boom! I use 35, should work for you.
Just a few sand bags in the back. And yes, 4x4 with LT tires
OVERKILL
$100 Site Donor 2021
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
And the tire doesn't know what vehicle it is on and the manufacturer of the tire doesn't know either. The placard spec is the appropriate pressure for a tire that fits the dimensions and specifications defined by the OEM and will subsequently yield the designed ride, handling and wear characteristics derived through OEM testing.
The pressure on the sidewall is there to indicate the pressure at which the maximum carrying capacity of the tire is achieved, nothing more. It is in no way a recommended pressure and this is made quite clear by all of the tire manufacturers.
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
And the tire doesn't know what vehicle it is on and the manufacturer of the tire doesn't know either. The placard spec is the appropriate pressure for a tire that fits the dimensions and specifications defined by the OEM and will subsequently yield the designed ride, handling and wear characteristics derived through OEM testing.
The pressure on the sidewall is there to indicate the pressure at which the maximum carrying capacity of the tire is achieved, nothing more. It is in no way a recommended pressure and this is made quite clear by all of the tire manufacturers.
Originally Posted By: otis24
1991 Chevrolet K1500. Original be tires were 225/75/16. Placard says 45 PSI. Currently running 245/75/16 tires. What should my PSI be?
225/75/16 at 45 psi had a specific designed load per tire to suit this vehicle load.
For similar designed load, a 245/75/16 of higher load rating would call for a pressure below 45 psi.
Without an actual calculation (by tire manufacturer),I would select anywhere between 42 and 45 psi.
JMHO.
1991 Chevrolet K1500. Original be tires were 225/75/16. Placard says 45 PSI. Currently running 245/75/16 tires. What should my PSI be?
225/75/16 at 45 psi had a specific designed load per tire to suit this vehicle load.
For similar designed load, a 245/75/16 of higher load rating would call for a pressure below 45 psi.
Without an actual calculation (by tire manufacturer),I would select anywhere between 42 and 45 psi.
JMHO.
Last edited:
Originally Posted By: maverickfhs
Originally Posted By: Wolf359
Originally Posted By: ammolab
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
Yeah, it's the other way around. The car maker knows the suspension and weight setup of the car. The tire maker has no idea. All they can do is specify a max. Go by whatever is on the door jam of the car. If it was up to the tire maker, you wouldn't even need a sticker, yet every car has one.
+1
+2
Originally Posted By: Wolf359
Originally Posted By: ammolab
Originally Posted By: BigCahuna
GO BY THE SIDEWALL OF THE TIRE. THE VEHICLE DOESN'T KNOW WHAT TIRE IS ON IT.,,
The tire side wall tells you the MAXIMUM pressure the tire can withstand...it has nothing to do with the propper pressure for running on any specific vehicle/load. Not a good recommendation!
Yeah, it's the other way around. The car maker knows the suspension and weight setup of the car. The tire maker has no idea. All they can do is specify a max. Go by whatever is on the door jam of the car. If it was up to the tire maker, you wouldn't even need a sticker, yet every car has one.
+1
+2
According to Tire Guides, a 1991 K1500 came with either LT225/75R16's inflated to 50 psi, or LT245/75R16's inflated to either 50 psi or 45 psi depending on the GVW.
Please note that there was no listing for an LT225/75R16 at 45 psi. So I am going to do the calculation both ways.
The load carrying capacity of an LT225/75R16 at 45 / 50 psi is 1790# / 1940#.
In order to carry the same load, an LT245/75R16 needs to be inflated to 38 / 43 psi.
- HOWEVER -
There is a school of thought that if you have enough load carrying capacity, it is better to match the spring rates of the tire by using the same pressure as on the placard. So I recommend using whatever is on the placard - and please check: No guessing.
Please note that there was no listing for an LT225/75R16 at 45 psi. So I am going to do the calculation both ways.
The load carrying capacity of an LT225/75R16 at 45 / 50 psi is 1790# / 1940#.
In order to carry the same load, an LT245/75R16 needs to be inflated to 38 / 43 psi.
- HOWEVER -
There is a school of thought that if you have enough load carrying capacity, it is better to match the spring rates of the tire by using the same pressure as on the placard. So I recommend using whatever is on the placard - and please check: No guessing.
No guessing. I checked the placard. It is listed at 45 PSI.
gathermewool
Site Donor 2025
Originally Posted By: BigCahuna
Sorry MR expert. Maybe they can change the name of this sight to yours?,,
LCDR Expert, thank you
Sorry MR expert. Maybe they can change the name of this sight to yours?,,
LCDR Expert, thank you
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