Visit our Popular Forums

interstateflyer · 09-09-2014, 06:12 PM

My 2014 Dodge RAM 1500 5.7 Hemi just hit 20K miles and I'm considering replacing the OEM Goodyear SR-A P275/60 R20 Standard Load tires with Michelin M/S2 LT275/65 R20 LR Es.

The door jamb sticker says to inflate the tires to 39 psi. The Goodyear sidewall say 44 psi max. I've been inflating to 44 psi while towing.

I've run the Michelin LTs at or near the max of 80 psi indicated on their sidewall on trucks and trailers.

Should I completely disregard the 39 psi door jamb guideline and go somewhere nearer 80 psi on the Michelins?

Farmer Dan · 09-09-2014, 06:33 PM

I have the LR E Michelins on both trailers and my '10 F150. I run all of them at 80 PSI per my tire man. He's been in the industry for 35 yrs. He says flex at lower than max inflation will shorten tire life due to more heat. The F 150 had P tires when new and I had troubles so I bit the bullet at 16K mi on them and replaced with the Michelins. I now have 60K + miles on them and will trade the truck or replace them with probably 45% tread left.
Dan

CapriRacer · 09-10-2014, 06:31 AM

First, I am not a fan of replacing P type tires with LT type tires - and the reason will be clear in a moment.

In order to carry the same load a P275/60R20 does at 39 psi, an LT275/65R20 needs to use 47 psi.

Now since the vehicle's spring, shock damping, and sway bars were designed around a 39 psi tire spring rate, using 47 psi is going to not only cause a rough ride, but the vehicle will tend to overcompensate when encountering a bump, making the vehicle slightly less predictable, handling-wise.

BoldAdventure · 09-10-2014, 08:29 AM

That's fine, a lot of guys on the Ramforum have gone up to that size tire and all usually inflate to somewhere near 55psi. You can disregard the door jam. I myself plan on switching to that size shortly.

The Goopyears are a terrible tire, and anyone with a Ram who has driven on them knows they kind of suck when towing. I don't have a problem with them when not towing, but they are soft and tend to float.

msmcv51 · 09-10-2014, 08:29 AM

Will rims designed to handle 47 psi be overstressed at 80 psi?

BoldAdventure · 09-10-2014, 08:33 AM

Quote:

Originally Posted by msmcv51

Will rims designed to handle 47 psi be overstressed at 80 psi?

Depends on which rims. The Chrome clads I have are rated to 65psi max.

Wayward · 09-10-2014, 09:29 AM

I have not figured out any formula for this.

I always put larger and higher load rating tires on my trucks even adding spring leafs or small lifts to get as much tire as I can.

Here is what I do now....

- Ask the tire installer to inflate them 20% below the maximum pressure and take a short drive out of the shop.

- Look carefully at the initial wear pattern on the tread surface. When the tire is new it is fairly easy to see if the tires are touching closer to the "crown" or on the outside edges.

- I then go up or down 5 psi or so, as needed and recheck after another short trip

- After a few iterations it eventually gets close. After a few thousand miles they might show a bit of more permanent wear pattern and I make the final adjustment before rotating the tires.

Phoenix · 09-10-2014, 12:55 PM

We have a 2008 Tundra with 275/65x18 tires. OEM was BFGoodrich Rugged Trails, a "P" (passenger car) tire with max pressure = 44 psi. They had a soft ride, but were squishy when towing, even when inflated to 44 psi. Plus, they wore out quickly, even though our pickup isn't driven hard.

I replaced the BFGs with same size Michelin LTX M/S2, load range "E" LT tires. I now run 55 psi in the fronts so they wear more evenly, and 65 in the rears when towing (which is about 90% of the time). With the new tires and higher pressures, I don't think the ride is significantly harsher. However, there is a noticeable increase in road feel through the steering wheel; and handling is greatly improved.

It does ride a little more like a truck, and a little less like a passenger car; but it's still rides like a limo when compared to "Hal", our old, 1978, Chevy, 3/4-ton crewcab pickup.

I wouldn't run 80 psi. However, I think you'll find that your pickup will handle better, and your new Michelins will wear more evenly; if you use 44 psi as a minimum, and add a few psi in proportion to your load conditions in accordance with tire charts.

interstateflyer · 09-10-2014, 09:51 PM

How do you determine the max pressure for your wheels ?

Sent from my iPhone using Airstream Forums

Wayward · 09-10-2014, 11:30 PM

Quote:

Originally Posted by interstateflyer

How do you determine the max pressure for your wheels ?

Should be stamped or cast on the inside of the rim.

I believe it is the max pressure to be used during mounting when stresses are high, not for normal driving inflation.

overlander63 · 09-11-2014, 02:00 AM

Quote:

Originally Posted by Wayward

Should be stamped or cast on the inside of the rim.

I believe it is the max pressure to be used during mounting when stresses are high, not for normal driving inflation.

I am pretty sure that's not the case.
Every tire I've seen has a warning not to exceed 40 psi when mounting.
If a wheel has a max pressure stamped on it, that is the max pressure for operating.

Photobum · 09-11-2014, 03:41 AM

I run my Michelins at 65psi on my F-150, same as the trailer tires. No problems and having the ten plys makes me feel safer. I have 170M miles on my truck and am on my third set of tires. They wear much longer and better than the original OEM tires that I replaced at 350 miles.

CapriRacer · 09-11-2014, 04:41 AM

Quote:

Originally Posted by Wayward

Should be stamped or cast on the inside of the rim.......

There is no requirement that wheels have such stamping and many do not. So don't be surprised if you can't find a maximum pressure stamped anywhere on the wheel.

interstateflyer · 09-11-2014, 07:42 PM

Quote:

Originally Posted by CapriRacer

First, I am not a fan of replacing P type tires with LT type tires - and the reason will be clear in a moment.

In order to carry the same load a P275/60R20 does at 39 psi, an LT275/65R20 needs to use 47 psi.

Now since the vehicle's spring, shock damping, and sway bars were designed around a 39 psi tire spring rate, using 47 psi is going to not only cause a rough ride, but the vehicle will tend to overcompensate when encountering a bump, making the vehicle slightly less predictable, handling-wise.

Where can I read more about the negative impact of handling when using a stiffer tire with higher pressures?

Photobum · 09-12-2014, 05:24 AM

Try calling Michelin....

We'll gladly assist with load / pressure when towing a trailer. We recommend having the vehicle weighed with the trailer attached.

Please provide the tire size and the total weight.

Thanks again for writing a review and thank you for choosing Michelin.

It is our goal to ensure that your issue has been resolved or your question answered to your satisfaction. If we can assist you further, please respond to this email or call us at 1-866-866-6605 (toll free) between 8:00AM and 8:00PM Eastern Time Monday through Friday or between 8:30AM and 4:30PM Eastern Time on Saturday.

Lance M · 09-12-2014, 11:28 AM

I posed the question to a towing expert "What is the best 20" tire for towing with my new RAM 1500?"
His advice was to go with a Yokohama P275/55/20XL.
I'm interested to hear how the Michelin LTX M/S2 LT275/65/20LRE work while towing. Since my RAM has 3.92 gears, I think I'd prefer the taller tires for gearing, but not if the ride and handling suffer.

Sent from my iPhone using Airstream Forums

BoldAdventure · 09-12-2014, 06:40 PM

Top, Interstateflyer do some reading over on the ramforums dot com. A lot of guys running that and a good discussion on that size tire in the towing area under 4th gen trucks (our trucks).

The ride difference is marginal. You'll notice it harsher over speedbumps, pot holes, those sort of things. Most say there is no real noticeable change cruising down the high way.

I'll be switching to 275/65/20 General Grabber ATII's or Cooper Zeon LT's shortly. I'm starting to lean more towards the Zeon's after reading a lot of reviews. They're more of a highway tire with minimal offroad traction, considered a hybrid and not a true AT.

Lance M · 09-12-2014, 06:55 PM

Do you mean ramforumz.com? With a "z"?

BoldAdventure · 09-12-2014, 06:57 PM

sorry no S just ramforum, but the Z one is good, too, just to many ads for my tastes, lol.

I think I've found about 5 dodge truck related forums, but those two are the most active by far.

interstateflyer · 09-15-2014, 03:41 PM

America's Tire/Discount Tire's data base says that since the Michelin LT275/65R 20E are 1 inch greater diameter than the P275/60R 20 that they would replace......they could hit the inside of the wheel well when turning.

Also, my dealer says that it could affect the shift pattern, speedometer and other issues which they may not be able to program out.

So, it looks like any 20 inch LT275/65 LR E is out of the question for a 2013 RAM 1500 Outdoorsman 2x2.

How MUCH of an improvement do you guys think the Michelin LTX P275/60 R 20 would be over the OEM Goodyear Wrangler SR-AS P275/60 R 20?

I've gotten 16,000, sometimes white knuckle miles towing miles (21,000 total) out of the Goodyears and I'm ready for a change.