This is on my lt's

So I noticed that they were riding a little rough at 38psi and took them down to 35psi....well not to much changed.


I went to were I bought them and talked to the so called "manger" about how the tires changed my ride so much. Well he told me to set them at 30 rear, & 30 or 32 front.

Before I do this...a few question's

Isn't this kind of low for an LT tire?

I assume this will affect on how the tires wear? (IE. A lot faster with the lower pressure?)


Thanks

 

As you have an '06 you do not have the TPMS sensors to worry about. Yes they will wear faster on the outside edges. Under-inflated tires is the #1 cause of blowouts as the tires flex so much more. Flexing generates heat, which leads to the separation of the ply. From page 164 of the '06 owners manual;

"Utility vehicles have a significantly higher rollover rate than
other types of vehicles. To reduce the risk of serious injury or
death from a rollover or other crash you must:
• Avoid sharp turns and abrupt maneuvers;
• Drive at safe speeds for the conditions;
• Keep tires properly inflated; (added bold)
• Never overload or improperly load your vehicle; and
• Make sure every passenger is properly restrained"

From page 169;

"Under-inflation is the most common cause of tire failures and
may result in severe tire cracking, tread separation or blowout,
with unexpected loss of vehicle control and increased risk of injury.
Under-inflation increases sidewall flexing and rolling resistance,
resulting in heat buildup and internal damage to the tire. It also may
result in unnecessary tire stress, irregular wear, loss of vehicle control
and accidents. A tire can lose up to half of its air pressure and not
appear to be flat!"

Also from page 169;

"Always inflate your tires to the Ford recommended inflation pressure
even if it is less than the maximum inflation pressure information found
on the tire. The Ford recommended tire inflation pressure is found on
the Safety Compliance Certification Label or Tire Label which is located
on the B-Pillar or the edge of the driver’s door. Failure to follow the tire
pressure recommendations can cause uneven treadwear patterns and
adversely affect the way your vehicle handles."

Now who would you believe the "manager" at the shop or Ford?
It's a truck, if the ride is not soft enough for you maybe you need to be driving a Lincoln.

 

That is exactly what I was thinking....I was reading also that an LT tire needs more air pressure to run cooler at the same temp then a P does.


As far as needing to be driving a Lincoln I dont think so

I had P rated generals before these LT's.....ride difference is HUGE. I knew the difference would be smoe what stiffer but I did not think this much. With the LT's at 40psi going down the freeway I feel like I was riding in a lumber wagon with NO suspension, it is that bad. I literary had to hold my spleen from falling out. On certain roads that the generals would glide over the LT's feel like I am on a bucking bull.

Don't get me wrong, the generals were a piece of ***** tire and I the LT's have 10x better traction and are also very quite for being an more aggressive thread . But the ride Is killing me from the generals I had.


I did air them down to 30r/32f last night a took a drive and I could notice BIG difference in the way it ride, much better that is. But I am worried about the psi, I mean I don’t what to risk the safety of me and my passengers because I have to keep the air down to get a good ride. Also wear would be 5x times as fast with the tires at that psi and most likely wont last very long.


I think I will be going back to the tire place and see what they can do for me.

 

sorry they ride rough for you...and that Service Manager is an idiot.

He needs to be corrected before he kills someone. A reference to the whole Exploder/Firestone incident in the South in 2000-2001 should be enough. Heat + low PSI is just dangerous


another option might be the Goodyear Silent Armour. I just bought them for my SUV on Friday. A P-265/70/17 (32" tall). They ride very very nicely and are a world of improvement over the Wrangler SR/A they replaced. Supposedly the Silent Armour is the new version of the Wrangler AT/S.


edit: wonder why your ride is that rough though. I run 45 psi up front and 42/43 psi out back....been that way since new, and they are wearing just about perfectly for me

 

Tylus, As for the service manger, he looked like an idiot too if you know what I mean.... Also when I tired them at 30psi I noticed a vid in the wheel and that the truck seemed kind of squirrly...NOT a good sign.

Yeah, I really wanted to give the LT a try but I think I am second guessing myself... I mean I really like the tire as far as thread design and traction in the snow, very quite at 70 mph, but the ride is getting to me.

I looked the paper work and it says right on it 40f 40r. I knew 30 sounded way low and I really did not want to put them that low to begin with. But since then I put them back up to 38f/r.

I Think I am going to go in there Monday and see IF they would just put the same tire on in P or i am willing to pay the difference for another set which would be.

As Tylus mentioned the Silent Armour
OR

2-Michlin LTX at/2.....very good I hear
3-Bridgestone Dueler A/T Revo
4-Dueler A/T D695

 

...........

 

yeah they ride rougher but I don't think it's that bad.

I went through 2 sets of the crappy p-rated 18" BFG stock tires. Then I got the LT-rated wranger AT/S, sure the ride is stiffer. I run them at 44psi. I've only got a few thousand miles on them right now, but they seem to be wearing better than the BFG's. But now I also have Harley 22" wheels, so I run them in the summer, and stock rims in the winter.

 

I have LT tires on my 2007 F150 supercrew 4x4.

When empty I run mine at 40 front, 38 rear.....they are a little stiffer sidewalls than a P tire, but thats the point of an LT, so it can carry a load.

When I have a lot of weight in the truck, or am towing with a high hitch weight I add air as required.
Maybe as high as 65 rear, 55 front.

 

WOW, just ran across this article online, it is a very good read.

Needless to say I will be going to discount in the morning at raising a little hell for telling me to run them at 30 psi!!!! Damn IDIOTS!!!! ::


http://www.nittotire.com/assets/safe...t%20Trucks.pdf

 

just a thought here, but you thought of throwing in some weight?? if your like my dad he is lucky to carry a shovel and tow chain. set a couple of old inner tubes with sand in em (tied ends with wire) they won't slide around or rattle easy to remove when he does ever haul anything and he's got sand for iciy conditions.

 

just a thought here, but you thought of throwing in some weight?? if your like my dad he is lucky to carry a shovel and tow chain. set a couple of old inner tubes with sand in em (tied ends with wire) they won't slide around or rattle easy to remove when he does ever haul anything and he's got sand for iciy conditions. I am sure you would rather have the capacity of them lts over ps.

 

sorry for the double posts was multitasking (watching super bowl pregame) don't know what happened... duhh operator errror..

 

I did think about that but I use my bed too much and that would just get in the way....but your dad sounds like my dad

 

Are these stock size tires or oversized? If they are oversize then the service manager may be more right than you are giving him credit for. Oversize tires render the factory pressures (in the manual an on the placard) moot. It's a lot more complicated than the references cited so far, though if you read that Nitto document carefully, you'll see a lot of what you are about to read. If you do a diligent web search, you can find much of what you will read also, though this comes mostly from tire manufacturers.

It's the VOLUME of air in the tire that carries the weight, not PRESSURE. Pressure is the indicator of volume and changes according to the size of the vessel in which the volume is placed. It takes X cubic feet of air to support Y pounds. If you put that volume into a smaller vessel (a smaller tire) it indicates a higher pressure than that same volume in a larger vessel (a big tire). What that means is the bigger tire can carry the same weight with less pressure but there's more to it. To get teh details, which accounts for the construction differences between different tires, you need what's called a load/inflation chart. This is a chart that lists the required inflation pressure to carry various weights according to the tire size. The Tire and Rim Association has them and each tire manufacturer will have them for their individual tires. Not always easy to get, however. Let's crunch some numbers.

Example: My '05 F150HD

The factory specifies a pressure of 50 front and 60 rear for the OE 245/70R17s for the maximum GVW of the truck, 8200#. No empty-truck pressures are given.

I consult a load inflation chart for that OE tire and find at 50 and 60 PSI, those tires can support 2205 and 2460 pounds each, respectively (that's 9,300# worth of tire capacity, by the way, on an 8,200# rating).

I then consult the load inflation chart for the new tires, Dick Cepek FCII LT285/70R17

At 50 and 60 PSI, they can support 2,755 PSI and 3,070 PSI, each, respectively.

To match the OE load capacity with the new tires, the inflation chart tells me I need about 37 PSI front and 41 PSI rear. That's the difference in the size of the vessel talking. Both new and old tires have approximately the same volume of air in them. But these pressure are for a max GVW. What about an empty truck?

When I weigh the truck with individual scales at each wheel, I find, empty, with about half a tank, my normal tools and no driver, the truck has the following weights:

LF 1727#, RF 1647#, LR 1200#, RR, 1233#

When I work that out with the new tires, to match the empty weight, I only need about 28 front and about 21 rear. With the old tires I need 35 front and about 25 rear. Obviously, you have to account for the extra weight of a full tank, driver and a coupla passengers, etc, but that's the snapshot at that weight.

You can get exact numbers, between the PSI listed on the charts (usually in 5 PSI increments) by dividing the load rating in pounds near the value you are considering, and divide by the PSI. That gives you the pounds per PSI. You then divide the measured weight (for each tire) by the pounds per PSI number to get a working pressure. You should do this with a load value on the chart nearest the actual weight because the charts aren't always linear.

Most tire people want you to boost up 10-12 percent or so from whatever you get with a load/inflation chart as a starting point at any given weight, for a safety margin. Also, no one will deny that a pumped up tire will deliver better fuel economy. I also like to air up a little extra just in case I toss in a light load. It also gives you a margin for the slight pressure loss that all tires have over time and to account for variations of seasonal temperature (though in both of these cases, if you check you pressure regularly, as you should, these are not issues).

The final test of any pressure is to find a straight section of freeway on a warm (not hot) day, stop and let the tires cool off to as close to ambient temp as possible ( I have used buckets of water to speed that process). Measure the tire pressure (and temp if you have a infrared gun) then go down the road at legal speeds above 60 mph for 10 -15 minutes. Recheck the pressure. If it's risen more than 10 percent (roughly 50 degrees, tire pressure rises about 1 psi per 10 degrees) then you need more air. Add pressure in 5 PSI increments until you get the right temp numbers. You have to let the tire cool back down to ambient to recheck (your test will be the pressure should be what you originally started with plus what you added). Yes, this requires time, patience, judgment and a little brain power and that's why most people don't bother. But this is one method and element in the testing the OE and tire mfrs use to determine their rated tire pressures.

In the end, you are always SAFE with more air, but you may not get the best ride or tire wear. Many people run around with enough pressure to carry 12,000 pounds on a truck that weighs less than half that.

Just thought you'd like to know before you jump that poor service manager.

 

Thanks, that is a lot of good info.


Tires are LT265/70/17 load range c

Factory was P255/70/17


I am about to head off and I will try to keep my cool.


Again , Thanks a bunch for the info Jim Allen