Post by: Nick1911 on August 15, 2008, 04:45:02 AM
So I got a replacement tire, and drove it home. When I got home, I decided to check tire pressure, since I wanted the back two tires to be at roughly the same pressure. Results:
New tire: 42 psi
Old rear tire: Off scale, estimated 80 psi
Front left: 55 psi
Front right: 60 psi
Now, I've only ever had cars; and in my cars I run the tires between 32 and 40 psi. The sidewalls say that max weight (3042 lbs per tire) is achieved at 80 psi, but I don't run a lot of weight in the truck. Someday, I might move some heavy machinery, but the normal load is under 500 lbs.
Questions:
- Can anyone recommend an inflation pressure?
- Is there some kind of chart that compares tire psi with load weight?
- Would running a tire at it's maximum pressure, lightly loaded increase the chance of a blowout?
- Should all tires be inflated the same, or should the back tires be inflated more?
Thanks!
Post by: Scout26 on August 15, 2008, 05:10:19 AM
Old rear tire: Off scale, estimated 80 psi
[Jamie from mythbusters voice] Well there's your problem.....[\voice]
RTFM, [
, sorry] i.e. Check in the owners manual for recommended pressures and/or the tire itself.
Post by: Nick1911 on August 15, 2008, 05:14:00 AM
Old rear tire: Off scale, estimated 80 psi
[Jamie from mythbusters voice] Well there's your problem.....[\voice]
RTFM, [
, sorry] i.e. Check in the owners manual for recommended pressures and/or the tire itself. Tire states maximum pressure and weight limit. Couldn't find a recommended pressure.
And I'm fairly sure that the truck didn't come with an owners manual.
Post by: Ben on August 15, 2008, 05:24:35 AM
I started a topic like this about a year ago here. Try and search for it -- I had several responses I believe.
Post by: zahc on August 15, 2008, 05:53:42 AM
In the absence of owners manual data, I fill them to that. At least the tire manufacturer is down with it. If I remember correctly the whole Firestone/Ford thing was a result of Ford recommending a tire pressure (to improve ride quality) that Firestone itself didn't recommend.
Post by: Tallpine on August 15, 2008, 06:01:05 AM
If I were to be hauling a big load for a distance, I probably run the back ones up to about 75psi.
The 10 ply tires hold up great on these gravel roads, whereas everything else we have gets flats all the time
Post by: 41magsnub on August 15, 2008, 06:17:19 AM
FWIW, I run about 60psi in my old C-20. That takes care of most loads without being too harsh.
If I were to be hauling a big load for a distance, I probably run the back ones up to about 75psi.
The 10 ply tires hold up great on these gravel roads, whereas everything else we have gets flats all the time
If I were to be hauling a big load for a distance, I probably run the back ones up to about 75psi.
The 10 ply tires hold up great on these gravel roads, whereas everything else we have gets flats all the time
I do the exact same but my 10 plys were an accident since I am more of a city boy except for when I'm not. The tire guy: "for $9 more per tire you can go from 6 ply to 10 ply!" Me: "cool!" Me driving home: "Jeebus, this thing sure rides like a truck now and what the hell is that rumbling?" Not gonna get a flat though!
Post by: Scout26 on August 15, 2008, 07:00:56 AM
And I'm fairly sure that the truck didn't come with an owners manual.
http://www.motorcraftservice.com/vdirs/SPubs/default.asp?pageid=oghome&gutsid=spubs_serv_all_new&TYPE=OWNERGUIDE
Post by: Thor on August 15, 2008, 07:08:57 AM
Post by: Nick1911 on August 15, 2008, 07:13:17 AM
While I don't have an F250 with the high pressure tires, I DO have an F150. I keep them at the tire pressure indicated on the sidewall. (A throwback from my days in Naval Aviation). I've been told that I SHOULD keep them at the recommended tire pressure found on the driver's side door frame. Regardless, I have almost 50K miles on the factory original tires. It's almost time for some new tires, but I still have some decent tread left.
Would that be the maximum pressure?
And I'm fairly sure that the truck didn't come with an owners manual.
Links to an error page.
I did some searching and found it available for $16.
http://www.motorcraftservice.com/vdirs/SPubs/default.asp?pageid=oghome&gutsid=spubs_serv_all_new&TYPE=OWNERGUIDE
Post by: Brad Johnson on August 15, 2008, 08:06:59 AM
As has been suggested, look inside the door jambs. One or the other will have a sticker that indicates the mfg suggested pressure. If your tires are factory size, use that and adjust as necessary for load/comfort.
Brad
Post by: mgdavis on August 15, 2008, 08:25:52 AM
) the label in the drivers side door jamb calls for 36psi in all four.If you told us what year the truck was, it'd be easy enough to dredge up an answer with Google.
Post by: richyoung on August 15, 2008, 08:58:07 AM
This gives you the maximum load-bearing weight of the tire - remember, as you turn, accelerate, and brake, the load on each individual tire changes. Being at max gives you more wiggle room to prevent a blowout due to an extreme dynamic load condition.
The tire will run cooler, with less sidewall flex, making it less prone to blowout and increasing life of the tire.
Maintains the pressure on the ground of the center of the contact patch.
Best gas mileage.
Reasons NOT to run max pressure are:
Ride comfort.
The axle the tire is on is lightly loaded, and max pressure prevents the inner and outer edges of the contact patch from putting full pressur on the ground, causing traction, handling, and tire wear issues.
An attempt to adjust understeer/oversteer characteristics of the vehicle with differential pressure.
Different brand/construction of tires on different axles.
Best way to tell if you are over or under inflating that is available to normal people is a chalk test. Take a crayon or piece of chalk, and mark the trad of each tirefrom a couple of inches in from the outer edge to a couple of inches up the outer sidewall, a couple of inches wide. Drive a few blocks, including turns in both directions, and stop and look at the markings:
If the markings are worn off right where the tread stops and the sidewall begns, the inflation is good for those load conditions.
If the chalk extends past the sidewall and onto part of the outer edge of the tread, the tire is overinflated for those conditions.
If the markings are erased accross all of the tread, and partially up the sidewall, the tire is underinflated.
Remember - all pressures are COLD - bumo them up 2 lbs per 35 pounds of pressure if the tires are hot.
Post by: anygunanywhere on August 15, 2008, 10:31:54 AM
I highly recommend sticking with the recommended pressure up front. You can fudge a little on the rear if you want a smoother ride but if yuo load it down you need to air up. Those sidewalls need the pressure with the load increase.
Anygunanywhere
Post by: Hawkmoon on August 15, 2008, 08:39:06 PM
Generally, you want to run the MAXIMUM presure on the sidewall, unless there is a good reason not to. The reasons for this are:
This gives you the maximum load-bearing weight of the tire - remember, as you turn, accelerate, and brake, the load on each individual tire changes. Being at max gives you more wiggle room to prevent a blowout due to an extreme dynamic load condition.
The tire will run cooler, with less sidewall flex, making it less prone to blowout and increasing life of the tire.
Maintains the pressure on the ground of the center of the contact patch.
Best gas mileage.
This gives you the maximum load-bearing weight of the tire - remember, as you turn, accelerate, and brake, the load on each individual tire changes. Being at max gives you more wiggle room to prevent a blowout due to an extreme dynamic load condition.
The tire will run cooler, with less sidewall flex, making it less prone to blowout and increasing life of the tire.
Maintains the pressure on the ground of the center of the contact patch.
Best gas mileage.
Generally, you do NOT want to run the maximum pressure listed on the sidewall, because that's the pressure to be used only when carrying the maximum rated load.
Yes, it gives you the maximum carrying capacity. Which you don't use or need most of the time.
The tire will be riding only on the center of the tread, not the full width. Far from enhancing your control and tire life, you have LESS rubber in contact with the road, worse steering, worse braking, and the center of the tire wears out while you still have lots of tread on the shoulders.
You will get better gas mileage, though.