When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
There is a lot of good info on this thread about pressures. If you really want to know what you should run, get your truck weighed front and back. Then use the load chart to figure out what psi you need in order to support the unloaded weight of your truck plus a safety margin.
My truck, for instance. I NEED 40psi front and 35psi rear to support the weight of the truck, passengers plus a 500ish lb safety margin. I don't go that low but I do run 48F and 42R which puts me well above what the tires are actually carrying and the ride is great. You absolutely do not need 80 and 70 just driving around unloaded.
Up to you to do the math and figure out what you actually need but I assure you, it's nowhere close to 80/70 unloaded.
Thinking of dropping 10 lbs from door jam: F 90 lbs/R 80 lbs. WHY? better, smoother ride, when loaded I run door jam. Thoughts???
Your Front GAWR is 6,000lbs, actual weight is probably closer to 5,000lbs. Per Continental’s load table, the 225/70r19.5 in a single tire setup will support 3,040 lbs per tire at 75 PSI (6,080 for the pair). That is higher than the GAWR.
At the door jamb sticker 90 PSI, it’s 3,450 lbs (6,900 total). Oddly enough, C&C F450’s with the same front axle have a 7,000 lbs front GAWR.... They might have different springs though. .
For the rear, GAWR is 9,900 lbs. The table says that at the sticker’s 80 PSI, each tire will support 3,000 lbs in dual mode (12,000 lbs total, 9,000 lbs with a single tire failure). At 70 PSI, it’s 2,720 per tire in a dual (10,880 total, but only 8,160 if one tire fails). Rear unloaded weight is probably around 4,000 lbs, so well below even the 70 PSI number.
Of note is the fact that you can’t get both axles to their GAWR without exceeding the GCVR.
70 PSI is the lowest number in the table, which is the minimum PSI per Continental. You could extrapolate weight capacity at sub-70 PSI levels, but that is likely not advisable.
I run 10 under my door sticker on my 2020 F-250. What was surprising to me is even though the fronts start 5 psi less than the rear by time I drive 10 miles the front is higher than the rear due to the weight of the diesel.
I run 10 under my door sticker on my 2020 F-250. What was surprising to me is even though the fronts start 5 psi less than the rear by time I drive 10 miles the front is higher than the rear due to the weight of the diesel.
What truck configuration, tire size, and what does the door sticker say?
Assuming an F250 4x4 CCSB, the max front GAWR is 5,200, with a base curb weight around 4,500 lbs (XL with no options probably). If you have the 275/70r18, minimum pressure would have to be 40 PSI to support 4,540 lbs. 50 PSI gets you to 5,360 lbs, which is over the GAWR with a 3% cushion.
If you door sticker says 50 and you take 10 off, you are down to the bare-bones minimum. A well optioned truck would probably be heavier in the front end, which would require 42, 43, or even 45 PSI to carry the load. That might be why you are seeing front pressures spike due to heat build up (under-inflated.)
Your Front GAWR is 6,000lbs, actual weight is probably closer to 5,000lbs. Per Continental’s load table, the 225/70r19.5 in a single tire setup will support 3,040 lbs per tire at 75 PSI (6,080 for the pair). That is higher than the GAWR.
At the door jamb sticker 90 PSI, it’s 3,450 lbs (6,900 total). Oddly enough, C&C F450’s with the same front axle have a 7,000 lbs front GAWR.... They might have different springs though. .
For the rear, GAWR is 9,900 lbs. The table says that at the sticker’s 80 PSI, each tire will support 3,000 lbs in dual mode (12,000 lbs total, 9,000 lbs with a single tire failure). At 70 PSI, it’s 2,720 per tire in a dual (10,880 total, but only 8,160 if one tire fails). Rear unloaded weight is probably around 4,000 lbs, so well below even the 70 PSI number.
Of note is the fact that you can’t get both axles to their GAWR without exceeding the GCVR.
70 PSI is the lowest number in the table, which is the minimum PSI per Continental. You could extrapolate weight capacity at sub-70 PSI levels, but that is likely not advisable.
Went to the tables and 70 all the way around would be doable, of course, the min I load up and got to pump up!
What truck configuration, tire size, and what does the door sticker say?
Assuming an F250 4x4 CCSB, the max front GAWR is 5,200, with a base curb weight around 4,500 lbs (XL with no options probably). If you have the 275/70r18, minimum pressure would have to be 40 PSI to support 4,540 lbs. 50 PSI gets you to 5,360 lbs, which is over the GAWR with a 3% cushion.
If you door sticker says 50 and you take 10 off, you are down to the bare-bones minimum. A well optioned truck would probably be heavier in the front end, which would require 42, 43, or even 45 PSI to carry the load. That might be why you are seeing front pressures spike due to heat build up (under-inflated.)
F250 CCSB 6.7 Lariat with HCTT, door reads 60 front and 65 rear, I’m testing 50/55 PSI. 275/65R20. I’m not worried about the weight as the truck is really overkill for what it use it for, I was just surprised how much the weight of the diesel boosted the pressures.
REAR: Door jam calls for 80 psi and that is where it is at, but LOOK closes at the outer tread on both tires and both edges, note the dark black which is rubber that did not pick up the dust on the center tread. My guess is I can take off 10 psi bringing it down to 70 and get a full dust line across the contact patch FRONT: Door jam calls for 90psui, I dropped it to 80, then 70psi and it looks great at that point. Full dust across the Contact patch.
70 psi all the way around on this '20 F 450 King Ranch as equipped...
There is a lot of good info on this thread about pressures. If you really want to know what you should run, get your truck weighed front and back. Then use the load chart to figure out what psi you need in order to support the unloaded weight of your truck plus a safety margin.
My truck, for instance. I NEED 40psi front and 35psi rear to support the weight of the truck, passengers plus a 500ish lb safety margin. I don't go that low but I do run 48F and 42R which puts me well above what the tires are actually carrying and the ride is great. You absolutely do not need 80 and 70 just driving around unloaded.
Up to you to do the math and figure out what you actually need but I assure you, it's nowhere close to 80/70 unloaded.
... If you really want to know what you should run, get your truck weighed front and back. Then use the load chart to figure out what psi you need in order to support the unloaded weight of your truck plus a safety margin.
REAR: Door jam calls for 80 psi and that is where it is at, but LOOK closes at the outer tread on both tires and both edges, note the dark black which is rubber that did not pick up the dust on the center tread. My guess is I can take off 10 psi bringing it down to 70 and get a full dust line across the contact patch FRONT: Door jam calls for 90psui, I dropped it to 80, then 70psi and it looks great at that point. Full dust across the Contact patch.
70 psi all the way around on this '20 F 450 King Ranch as equipped...
This is the best way to see if your pressure is correct. You can actually observe the contact patch where it either is or is not in contact.
This is the best way to see if your pressure is correct. You can actually observe the contact patch where it either is or is not in contact.
YEP and I trust my eyes!
YEP, dad taught me that when I got old enough to get on the old Ford 9n tractor and drive those ranch trucks. Charts, there weren't no stinkin charts, few folks had an air compressor and unless you have fixed a flat on a tractor tire, then pumped it up with a bicycle pump you don't know what a long day is.
If you had a gage, its was pencil gage and I defy you to get the same reading twice on the same tire.
On my Jeep TJ, with 37 x 12:50 x17 BFG KM2 I ran 16-18 psi to get a full contact patch, offroad I ran 3-5 psi...the chart does not give you all the answers.
