2011 XLT wallowing on highway

[ExpeditionAndy]

I think maybe you meant actual load, not load capacity?

This is turning out to be more complicated than I thought now that I'm really thinking it through and looking up charts for my tires etc. Who knew tires were so complicated?

This article isn't specifically for LT tires but seems to hit the topic hard.
https://www.4wheelparts.com/tire-wheel-package-guide/tire-pressure-checker.aspx

One aspect of the idea seems to be to achieve the proper tire/road contact area for wear etc. I noticed as I increased the pressure today to 44 psi, much less of the tire was "touching the pavement". But I don't really know how much should touch so ??? Now I'm going to be looking at everybodys tires in parking lots for the next week! I was doing that at Wegmans today and a nice lady stopped to make sure I was OK. She thought I had fallen. It almost worked out great for me! LOL

Also interesting discovery was finding out that one tire was down to 22 psi when I started out. This is with the new install last week. So I guess I might a slow leak and need to monitor. Or maybe the tire shop failed to inflate properly? Will monitor that and find out.

Well the chart here shows the actual starting pressure which is based on the weight of the vehicle and the load bearing weight of the factory tires, for example if the factory tires are set for 2450 lbs each then you add pressure until the LT tires are pumped up enough to support that weight.

I found the chart and quote it here: http://www.expeditionforum.com/posts/281108/

From: @AllBoostNoEco, post: 281108, member: 55576

Stock tire size is P275/55R20, which is load rated at 2403 pounds at 35 PSI in a passenger car application. Since it’s on an SUV, you divide that by 1.1 due to downrating of P-metric tires in an SUV/light truck application. That gives you 2,185 pounds at 35 PSI.

The tire he is replacing it with is an LT285/65R20, which supports 2,180 pounds at 35 PSI. At 36 PSI, it supports 2,222 pounds. Thereby putting it slightly over the requirement for this application.

This info all came from the Tire and Rim Association Load application tables, which is the standard used by all tire and rim manufacturers in the US to rate their respective items.

I wanted to put this out there because there are always a lot of questions about how you truly determine proper inflation for an LT-metric tire in an application originally fitted with a P-metric one.

 

[Plati]

Wow .. probably easy for some to understand but definitely tests my fading brain. However, I read this as follows. In the above example the LT tire size was "bigger" but the psi was about the same for the load rating of the P tire. My situation is same size tires from P to LT. In the lower chart, if you look at the line for the same size LT tire, the recommended psi is 45 to 50 for the load rating vs 35 for P. So this confirms to me when I go from a P to an LT tire and keep the same size ... I need to increase the psi. Which is what you and others said. Maybe I can find the whole chart with my tire size on it and then determine actual recommended psi.

I also emailed the tire manufacturer TechSupport and asked the guy at Goodyear T&S today when I was in making my appointment to fix the slow leak. The guy at Goodyear only knew the "look on the door area plate" answer as if LT tire made no difference. I politely thanked him and left.

 

[rjdelp7]

Springs hold vehicle up. Shocks keep tires on the road. Your car rides on the air in the tire( yours sound like they may be over filled). Tires can affect, the ride. LT tires have an extra belt and plys. They ride terrible. A loose front end, can magnify issues at highway speeds.

 

[Adieu]

Well the chart here shows the actual starting pressure which is based on the weight of the vehicle and the load bearing weight of the factory tires, for example if the factory tires are set for 2450 lbs each then you add pressure until the LT tires are pumped up enough to support that weight.

I found the chart and quote it here: http://www.expeditionforum.com/posts/281108/

From: @AllBoostNoEco, post: 281108, member: 55576

Stock tire size is P275/55R20, which is load rated at 2403 pounds at 35 PSI in a passenger car application. Since it’s on an SUV, you divide that by 1.1 due to downrating of P-metric tires in an SUV/light truck application. That gives you 2,185 pounds at 35 PSI.

The tire he is replacing it with is an LT285/65R20, which supports 2,180 pounds at 35 PSI. At 36 PSI, it supports 2,222 pounds. Thereby putting it slightly over the requirement for this application.

This info all came from the Tire and Rim Association Load application tables, which is the standard used by all tire and rim manufacturers in the US to rate their respective items.

I wanted to put this out there because there are always a lot of questions about how you truly determine proper inflation for an LT-metric tire in an application originally fitted with a P-metric one.

2180 lbs max per wheel in a 3 ton 8-seater with cargo room aplenty and a tow rating of 9k pounds is ********.

Especially if you take her to highway speeds, since LTs have low, real-life-scenario achievable max speeds. Many vehicles actually have a second set of door stickers for high speed use.... yes on sport sedans its for ">100mph", but 100 mph on a Z rated tire is actually LESS in % of its max limit than 75 mph is on a truck tire


Inflating it to at the bare minimum to hold 2500 lbs, and preferably more like 3k lbs per wheel would be far more prudent

And, btw, your chart starts with some ridiculously oversized tires. The SMALLEST one in there is a 34"... and some of those entries are at least 38"

Most of this stuff simply cannot fit an expy without extensive mods

 

[ExpeditionAndy]

2180 lbs max per wheel in a 3 ton 8-seater with cargo room aplenty and a tow rating of 9k pounds is ********.

Especially if you take her to highway speeds, since LTs have low, real-life-scenario achievable max speeds. Many vehicles actually have a second set of door stickers for high speed use.... yes on sport sedans its for ">100mph", but 100 mph on a Z rated tire is actually LESS in % of its max limit than 75 mph is on a truck tire


Inflating it to at the bare minimum to hold 2500 lbs, and preferably more like 3k lbs per wheel would be far more prudent

And, btw, your chart starts with some ridiculously oversized tires. The SMALLEST one in there is a 34"... and some of those entries are at least 38"

Most of this stuff simply cannot fit an expy without extensive mods

Adieu, put the crack pipe down. This is not my chart, I reposted from a different discussion that somebody else posted and if you took the time to read all of the information that was posted with the tables you understand what the original poster was saying. The tire size of 275/55/20 is the current stock size on Expeditions unless they come with the 22" wheels. The original poster was showing how you take the original load bearing rating of the PMetric tires and lower the rating by 10% for SUV use that gives you an number, then you pump up your LTs to match that weight rating. IF you don't like it go complain to the Tire and Rim Association since you seem to be such an expert, because it is their chart.

 

[Adieu]

Adieu, put the crack pipe down. This is not my chart, I reposted from a different discussion that somebody else posted and if you took the time to read all of the information that was posted with the tables you understand what the original poster was saying. The tire size of 275/55/20 is the current stock size on Expeditions unless they come with the 22" wheels. The original poster was showing how you take the original load bearing rating of the PMetric tires and lower the rating by 10% for SUV use that gives you an number, then you pump up your LTs to match that weight rating. IF you don't like it go complain to the Tire and Rim Association since you seem to be such an expert, because it is their chart.

The Average American adult male weighs 195.7 pounds (as of 2014 data, and rising by an average of ~12 ounces a year in the period since 1960)

There's 8 seats and cargo room.

And a connection for a 9000 lb trailer. Which, as seen in some of the posts here, people regularly max out and even overload.....

Adds up to 9k lbs UNevenly distributed weight on the vehicle's wheels easy. Safety margin aint gonna be 2 or 5 or 10% in such conditions, more like +50%.


....so, uhm, yeah. Safe mixed-use set-and-don't-fret pressures would be for max weight 3500 lbs per wheel if you tow, 3000 lbs if you dont.

 

[Adieu]

PS and if you never do any of the above overloading, you dont need LT tires anyway

 

[Plati]

Springs hold vehicle up. Shocks keep tires on the road. Your car rides on the air in the tire( yours sound like they may be over filled). Tires can affect, the ride. LT tires have an extra belt and plys. They ride terrible. A loose front end, can magnify issues at highway speeds.

I have not found that the two sets of LT tires I have bought ride terrible, maybe some do? I've had the chance to compare Firestone Destination A/T (P rated) vs Kumho Road Venture AT51 (LT rated) on my 14 ExpyEL driving out to Rockies and back in summer and winter. I also have compared stock P rated Conti's vs Falken Wildpeak (LT rated) on my 2003 Expy driving locally. I actually think the LTs ride better on (both) my EXPYs in both summer and winter. Still tweaking with tire pressure setup so that might be a factor in my experience.

 

[Plati]

PS and if you never do any of the above overloading, you dont need LT tires anyway

I went to LT rated tires for 1) deeper tread 2) more rugged sidewall

Deeper tread (and severe snow rated) is advantageous in winter mountain driving
More rugged sidewall is advantageous on Forest Service Roads to avoid a flat

Obviously still struggling with tire pressure questions but everything in this world is a tradeoff
since I have zero need for increased loading.

Before buying the Kumho LT tires, I contacted their Tech Support, splained my logic, and asked if it was a mistake. I was told the following:
The LT version will be better for you if you are thinking that you will be doing a little bit more off-road driving than the average person. The sidewall construction is reinforced so you will get better handling in mud and dirt. However, with the deeper tread blocks and a heavier tire you will get a little reduced gas mileage and it will be slightly noisier. Comfort will be about the same. The AT51 was designed to achieve better noise reduction and comfort for an all-terrain product so you should be fine if this is a concern for you.

 

[AllBoostNoEco]

https://toyo-arhxo0vh6d1oh9i0c.stac...ication_of_load_inflation_tables_20170203.pdf

Here’s the chart. Explains how to do the math as well in the beginning.
@Polarizer if you have questions, PM me, I’m decent at doing the equations.

 

[Rockclutch]

I have not found that the two sets of LT tires I have bought ride terrible, maybe some do? I've had the chance to compare Firestone Destination A/T (P rated) vs Kumho Road Venture AT51 (LT rated) on my 14 ExpyEL driving out to Rockies and back in summer and winter. I also have compared stock P rated Conti's vs Falken Wildpeak (LT rated) on my 2003 Expy driving locally. I actually think the LTs ride better on my EL in both summer and winter. Still tweaking with tire pressure setup so that might be a factor in my experience.

I love my Falken AT3Ws, ride is excellent and noise is lower than the street tires that were on the truck when I bought it.

Running at 50psi and riding on Rancho 9ks .

Worth every penny.

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