Truck tire pressures

[Joe Walsh]

I'm hoping some of our members could help me with this question:

I just got the keys to a 'hand-me-down' 2003 Ford F150 Crewcab 4X4 truck.
It is my work vehicle supplied by my employer, as I sell and deliver industrial products.
They just put new tires on the truck prior to me receiving it, and they are Cooper LT265/70-R17 Discoverer ATR tires.
In the course of checking over the truck I found that the tires were inflated to 80 PSI!!!:eek:
I called the local Cooper tire distributor who installed them and they said: "We inflate them to the recommendations on the sidewall." (which says 80 psi for a full load capacity)
They also said that 'LT'/Light Truck tires have more plys in them and require high PSI inflation.
I'm not familiar with 'LT' tires and their ratings, but I can't believe that a truck tire runs more PSI than my Mtn. Bike tires!
The truck rides like a brick, so I dropped the pressures down to 50 PSI.

Anyone have any suggestions or experience with this type tire???

OEM tires were P265/70-17 with a recommended inflation of 30 psi Front/ 35 psi Rear.

[fastblackmerc]

Check the owners manual or the sticker on the door?

[Joe Walsh]

Yep, The sticker on the driver's door jamb is for P265/70-R17 tires:

30 psi front/ 35 psi rear

Owner's manual is MIA.

[nomad]

80 PSI seems a little high. Depends on what you're carrying.

FWIW, on my 2002 Chevy 2500 I ran 75 psi rears, 70 front. But, I also plowed in the winter and carried crap in the summer.

Tire dealers like to inflate to the max incase you decide to haul 1500#s around. You plow a tire and try to get them to replace it.

Run what feels good to you, within reason. On road trips,no payload, I would run 40 psi in mine no problems. FWIW

Disclaimer= I am not a tire dealer, as always use your own best sense.

[mrjones]

When I copied this in, it didn't come out very readable

Check out


http://www.goodyear.com/truck/pdf/databook/loadInflation.pdf


And look at page 7. 80psi is required for the maximum load for that tire, which is way over what the F150SC could handle. You'd be safe with much less than 80psi in the tire. 80psi is what you'd want in that tire if it were on an F350 pulling a 5th wheel camper.



SERVICE LOAD AND INFLATION TABLES
LIGHT TRUCK METRIC TIRES
FOR TRUCKS, BUSSES, TRAILERS AND MULTIPURPOSE PASSENGER VEHICLES USED IN NORMAL HIGHWAY SERVICE
Highway — 65 MPH TIRE LOAD LIMITS (LBS.) AT VARIOUS COLD INFLATION PRESSURES (PSI).
PSI
TIRE SIZE Radial Ply 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110
DESIGNATION Diagonal Ply, Bias Belted 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
Dual(D) TIRES MOUNTED ON 5° DROP CENTER RIMS
65 SERIES Single(S)
LT275/65*18 D 1765 1940 2100 2335(C) 2420 2570 2755(D) 2865 3010 3085(E)
S 1940 2130 2310 2535(C) 2660 2825 3000(D) 3150 3305 3415(E)
70 SERIES
LT255/70*16 D 1565 1720 1865 1985(C) 2150 2285 2470(D)
S 1720 1890 2050 2205(C) 2360 2510 2680(D)
LT265/70*17 D 1720 1890 2050 2270(C) 2360 2510 2680(D) 2735 2820 2910(E)
S 1890 2075 2255 2470(C) 2595 2760 2910(D) 3005 3100 3195(E)
LT275/70*17 D 1820 1995 2165 2335(C)
S 2000 2195 2380 2600(C)
LT305/70*16 D 2040 2245 2440 2680(D) 2805 2980 3195(E) 3320 3485 3640(F)
S 2270 2465 2680 2910(D) 3085 3275 3525(E) 3650 3830 3970(F)
LT315/70*16 D 2205 2355 2560 2835(D)
S 2405 2590 2815 3085(D)
75 SERIES
LT195/75*14 D 1015 1115 1210 1325(C) 1390 1485 1565(D)
S 1115 1225 1330 1435(C) 1530 1630 1710(D)
LT195/75*15 D 1060 1165 1265 1390(C)
S 1165 1280 1390 1520(C)
LT215/75*15 D 1225 1340 1460 1610(C) 1680 1785 1930(D)
S 1345 1475 1605 1765(C) 1845 1960 2095(D)
LT235/75*15 D 1390 1530 1660 1820(C) 1910 2030 2150(D) 2265 2375 2535(E)
S 1530 1680 1825 1985(C) 2100 2230 2335(D) 2490 2610 2755(E)
LT225/75*16 D 1365 1500 1630 1765(C) 1875 1995 2150(D) 2220 2330 2470(E)
S 1500 1650 1790 1940(C) 2060 2190 2335(D) 2440 2560 2680(E)
LT245/75*16 D 1545 1695 1845 2006(C) 2125 2255 2381(D) 2515 2640 2778(E)
S 1700 1865 2030 2205(C) 2335 2480 2623(D) 2765 2900 3042(E)
LT265/75*16 D 1740 1910 2075 2270(C) 2390 2540 2755(D) 2825 2965 3085(E)
S 1910 2100 2280 2470(C) 2625 2790 3000(D) 3105 3260 3415(E)
LT285/75*16 D 1940 2130 2310 2535(C) 2660 2830 3000(D)
S 2130 2340 2540 2755(C) 2925 3110 3305(D)
LT315/75*16 DS
2535(C) 2715 2950 3195(D)
80 SERIES
LT235/80*17 D 1570 1725 1870 2040(C) 2190 2315 2470(D) 2560 2685 2835(E)
S 1725 1895 2055 2270(C) 2405 2545 2680(D) 2815 2950 3085(E)
85 SERIES
LT215/85*16 D 1360 1490 1625 1765(C) 1865 1985 2150(D) 2210 2320 2470(E)
S 1495 1640 1785 1940(C) 2050 2180 2335(D) 2430 2550 2680(E)
LT235/85*16 D 1545 1700 1845 2006(C) 2125 2260 2381(D) 2515 2645 2778(E) 2885 3005 3085(F) 3230 3345 3415(G)
S 1700 1870 2030 2205(C) 2335 2485 2623(D) 2765 2905 3042(E) 3170 3300 3415(F) 3550 3675 3750(G)
LT255/85*16 D 1745 1920 2085 2270(C) 2400 2550 2755(D)
S 1920 2110 2290 2470(C) 2635 2800 3000(D)
*Tire size designation will include “R” (radial ply), “B” (bias belted) or “D” (Diagonal or bias ply). Notes: 1. Letters in parenthesis denote Load Range for which Loads are Maximum.
CAUTION – Always use Approved Tire and Rim Combinations for Diameters and Contours. See Page M-1 for Approved Rim Contours.
Sourced from 2002 Tire and Rim Data, ETRTO and Goodyear load inflation data.
L-7
LOADS

[ahess77]

The light-truck tires are meant for light-trucks capable of carrying 3000+ pound payloads. Since your truck isn't capable of carrying that kind of payload, it doesn't need the high tire pressures. But, since you don't have P(passenger) rated tires as identifed on the door sticker, you might want to add a few pounds over the 35psi just for good measure.

Here's the problem, your vehicles dynamics such as roll-over, collosion avoidance, stopping distances, etc. are all greatly affected by your tires and tire pressure. That's why you set the pressure to the door sticker and not the max pressure stated on the tire. That's why I'd suggest setting the pressure close to what the door sticker says.

I have a GMC2500HD and I run 80 psi rears and 60psi fronts just like the door sticker says. The tires are rated to handle 3014 pound load at 80psi. So, when I put 3000 pounds of gravel in the bed and am at 11400 pounds total, I want the tires to meet the max rated load capacity. Of course it rides like a rock when there's no payload, but it's less likely to roll over and when it does, my wife's lawyers will have an easier time getting her the $2 million I'm sure I'm worth.