Chalk Test
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Cross-Country
Joined: Oct 2017
Posts: 80
Likes: 7
From: Michigan
Chalk Test
When I got my 2017 F250 XLT SuperCab Long Bed 4 x 4 truck from dealer it had around 45 lbs pressure in all 4 tires.
I checked the door tag and it called for 60 lb in Front and 65 lb in Rear. So I cranked it up to the recommended pressures.
The Truck just about bucked me into the next county. The ride was very rough and bouncy. I decreased pressure to 58 Front and 55 Rear, which
resulted in a much more tolerable ride.
Then I did a little research and found out about the chalk
test, which I performed today. It ended up at 56 lbs in the Front and 50 lbs in the Rear. This test was done with nothing in the bed of the truck.
I don't tow very often and when I do it will only be a couple thousand pounds. May add a few more lbs in rear tires when I tow.
Haven't had a chance to road test yet.
Any one else perform this test on theirs?
I've included a link to a you tube video demonstrating how to do the Chalk test.
I checked the door tag and it called for 60 lb in Front and 65 lb in Rear. So I cranked it up to the recommended pressures.
The Truck just about bucked me into the next county. The ride was very rough and bouncy. I decreased pressure to 58 Front and 55 Rear, which
resulted in a much more tolerable ride.
Then I did a little research and found out about the chalk
test, which I performed today. It ended up at 56 lbs in the Front and 50 lbs in the Rear. This test was done with nothing in the bed of the truck.
I don't tow very often and when I do it will only be a couple thousand pounds. May add a few more lbs in rear tires when I tow.
Haven't had a chance to road test yet.
Any one else perform this test on theirs?
I've included a link to a you tube video demonstrating how to do the Chalk test.
Postmaster
Joined: Jan 2005
Posts: 4,424
Likes: 12
From: BC Canada
Chalk test is a good way to do it. The other good way, is to weight each axle, and look up the weight - psi tables for your tires and match psi to actual axle weights. Those door jam psi are for max weight, and they sure do result in a bouncy ride. I am down to 65 front and 65 rear for now..
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Cross-Country
Joined: Oct 2017
Posts: 80
Likes: 7
From: Michigan
Could you please provide me a link to the PSI Tables for a set of Goodyear A\T Wrangler Adventures size P275\70R18E.
I have found a couple tables but they don't show my tire size. I'm a little confused at how to figure this out using the charts.
I have found a couple tables but they don't show my tire size. I'm a little confused at how to figure this out using the charts.
More Turbo
Joined: Apr 2017
Posts: 628
Likes: 12
From: Madison WI
I'd be interested also as I have the same tires. GY only lists maximum pressure on their site.
Laughing Gas
Joined: Jul 2012
Posts: 1,210
Likes: 20
From: prince george, bc canada
This is a great way to test your pressures. I grew up when 32 PSI was a normal pressure! These high pressures are a way to achieve the highest mpg they can squeeze out. Unless you are hauling a heavy load these pressures are absolutely un necessary!! Those dam pressure monitors are a bitch though! With 35" rubber on 18" rims I run 35- 40psi highway and 25-30 off road. When I load up my 3000lb bigfoot camper I air up to 60psi.
Tuned
Joined: May 2017
Posts: 467
Likes: 48
From: Mount Arlington, NJ
This Toyo chart has just about all of the available sizes for Super Duty trucks, including many flotation sizes, but not all. Light truck tires start on page 22. OP's LT275/70R18E can be found on page 25.
https://toyotires-1524598101.netdna-...s_20151020.pdf
Those with F450s can check page 104 (actual page 3) for the 19.5 tire at this Bridgestone chart.
https://commercial.bridgestone.com/c...les%202015.pdf
https://toyotires-1524598101.netdna-...s_20151020.pdf
Those with F450s can check page 104 (actual page 3) for the 19.5 tire at this Bridgestone chart.
https://commercial.bridgestone.com/c...les%202015.pdf
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Posting Guru
Joined: Nov 2010
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From: 46th State
I've always had pretty good luck following the manufacturer's recommendation. I keep having to remind myself that I'm driving a truck not a limousine. I go more for fuel economy than ride comfort with 60 p.s.i. in all four (4).
More Turbo
Joined: Mar 2006
Posts: 582
Likes: 2
From: Eads, TN
Currently I'm running 60psi on all four corners, but I'm thinking about lowering the rears by 5psi. There really isn't a need to run the rears as much as the fronts. Fronts have the majority of the weight compared to the rears.
Cross-Country
Joined: Feb 2005
Posts: 97
Likes: 10
I agree yet we find disparity in that thought and what Ford recommends.
More Turbo
Joined: Mar 2006
Posts: 582
Likes: 2
From: Eads, TN
I believe Ford recommends the higher psi in the rears for liability reasons due to hauling or trailering weights.
Hotshot
Joined: Oct 2015
Posts: 19,687
Likes: 12,811
From: Wyoming
Mine is only unloaded when I'm driving in town which isn't often and is usually short trips. Otherwise, it has an 11K trailer on the rear hitch. I leave mine at 60/80 all the time so I don't have to futz with the pressures. The replacement of the OEM shocks with Rancho 9000XL's tamed the ride down enough that I don't notice any problems around town.
Posting Guru
Joined: Aug 2015
Posts: 2,399
Likes: 12
This Toyo chart has just about all of the available sizes for Super Duty trucks, including many flotation sizes, but not all. Light truck tires start on page 22. OP's LT275/70R18E can be found on page 25.
https://toyotires-1524598101.netdna-...s_20151020.pdf
Those with F450s can check page 104 (actual page 3) for the 19.5 tire at this Bridgestone chart.
https://commercial.bridgestone.com/c...les%202015.pdf
https://toyotires-1524598101.netdna-...s_20151020.pdf
Those with F450s can check page 104 (actual page 3) for the 19.5 tire at this Bridgestone chart.
https://commercial.bridgestone.com/c...les%202015.pdf