XR Xtreme Recon and High Tide -- tire pressure lesson learned

[Capt. Don]

After 4,500 miles of following the factory recommendation of 37 psi on my High Tide with XR suspensión, wheels and 35s, I called for help.
I talked with my Jeepero friends and family in Colorado about tire pressure for a JLU HT and told them I was running the factory recommended 37 psi. Steering was a bit twitchy and bumps went right to the suspension. They all asked me if I was stupid. 37 psi in the stock BFG 35s? They even pulled an AEV lift recommendation for 35s to be aired at 30 psi for street use. Even my wife kept saying something was not right with our new High Tide. I am big on following factory recommendations but …. OK, properly shamed and quite chagrined, I dropped the pressure to 32 psi and discovered a much happier Jeep (and wife). Bump stops aren’t the problem they are at 37 psi. Steering is less twitchy. Ride quality is far superior. Jeep tracks better down the road. Easier on tires and suspension and occupants on the broken asphalt and pot hole filled roads of this island. Better traction from the tires. I am much happier with my XR suspension now for such a minor change. Now I need to reprogram my LTPWS to accept 30-32 psi.

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[Chocolate Thunder]

The OEM tire pressure recommendation seems to be based strictly on mpg with no thought at all given to ride or handling.

37s @ 27 psi.

 

[Mocopo]

JLUR-XR right here, running at 31 psi! That also helps the ride quality when i do impromptu dirt roads that I want to just know where they go lol.

 

[Blacktip]

How does lowering tire pressure to 32 affect MPG and tire wear? I am following the man. recommendation and running at 37 for street driving, and I am only getting 15.5 MPG. I can't stomach lower MPG than that.

 

[KevinC11]

How does lowering tire pressure to 32 affect MPG and tire wear? I am following the man. recommendation and running at 37 for street driving, and I am only getting 15.5 MPG. I can't stomach lower MPG than that.

Higher air pressure means a less contact patch of rubber on the road. The less amount of rubber results in less rolling radius/resistance. It will increase gas milage on longer trips. It will shorten your tire life. It will be more prone to tire punctures. It's a trade off.

KevinC

 

[Dyolfknip74]

How does lowering tire pressure to 32 affect MPG and tire wear? I am following the man. recommendation and running at 37 for street driving, and I am only getting 15.5 MPG. I can't stomach lower MPG than that.

Google "tire chalk test" to find a happy medium.

 

[Old Jeeper]

PSI, here we go again:

Tire Sidewall PSI: This number reflects the MAX psi at the MAX load (weight on the tire)

Door Jam PSI: This number reflects the exact size and weight of your vehicle with this tire employed. If you move to a different tire this number no long reflects any degree of accuracy

How do you determine your exact PSI in a NEW Sized tire?

Several approaches.

1) You can CAT scale you Jeep with the new tires you have added. This will give you the weight on the rear axle and the weight on the front axle. Cost about $12.50 at most truck stops. Drive on, insure the rear axle is behind the front scale and push the button, tell them your name and company or whatever they ask for. Drive off, walk in and get you yellow sheet. Take the weights of each axle and divide by 2 to get the weight on each tire. Go to the MFG tire PSI - Weight Sheet and find your weight and psi. You may need to contact mfg to get a copy of the sheet

2) Water or dust: Flat surface, can be your driveway or parking lot wtih a wet spot, you drive thru inspect the tires to see where the water or the dust was left on the tire.

3) Objective: Full contact patch. If the width of the contact patch is not fully wet lower the psi. If completely wet or dusted as the case may be then increase the PSI. NOTE you do not wet over the outer edge of the tire.


Personal exp: My BFG KM2, 37x12:50x17 on my '03 TJR I did the wet and dust and the CAT scale and ended up with 16-18 psi street, 18-20 psi highway.

Below is for teaching points and how I do it on Jeeps and 450 truck. FACT this needs to be done anytime you change tire sizes that are outside the parameter of the OEM and then link tha to the Mfg recommendations for PSI to weight.


Black is wet, white is dry, psi was 110 psi and I lowered it to 70-75 psi for street and hwy.

37x15:50x17 BFG KM2 16 psi, full contact patch, no bulging on sidewalls, drive perfect

F 450 Truck loaded out for travel

Typical Weight - PSI Mfg spec Product Data Guide, Contential Commerical tires I use on my F 450, circled in green is my tire size

 

[Capt. Don]

How does lowering tire pressure to 32 affect MPG and tire wear? I am following the man. recommendation and running at 37 for street driving, and I am only getting 15.5 MPG. I can't stomach lower MPG than that.

17-18 in town with a light foot and pretty easy to see 23-24 mpg at 60 mph with a level road running 37 psi. I will monitor over the next month at 30-32 psi and report. This is with 4.56 gears, 1.5” lift, eTorque V-6 and 850re trans.

 

[Capt. Don]

PSI, here we go again:

Tire Sidewall PSI: This number reflects the MAX psi at the MAX load (weight on the tire)

Door Jam PSI: This number reflects the exact size and weight of your vehicle with this tire employed. If you move to a different tire this number no long reflects any degree of accuracy

How do you determine your exact PSI in a NEW Sized tire?

Several approaches.

1) You can CAT scale you Jeep with the new tires you have added. This will give you the weight on the rear axle and the weight on the front axle. Cost about $12.50 at most truck stops. Drive on, insure the rear axle is behind the front scale and push the button, tell them your name and company or whatever they ask for. Drive off, walk in and get you yellow sheet. Take the weights of each axle and divide by 2 to get the weight on each tire. Go to the MFG tire PSI - Weight Sheet and find your weight and psi. You may need to contact mfg to get a copy of the sheet

2) Water or dust: Flat surface, can be your driveway or parking lot wtih a wet spot, you drive thru inspect the tires to see where the water or the dust was left on the tire.

3) Objective: Full contact patch. If the width of the contact patch is not fully wet lower the psi. If completely wet or dusted as the case may be then increase the PSI. NOTE you do not wet over the outer edge of the tire.


Personal exp: My BFG KM2, 37x12:50x17 on my '03 TJR I did the wet and dust and the CAT scale and ended up with 16-18 psi street, 18-20 psi highway.

Below is for teaching points and how I do it on Jeeps and 450 truck. FACT this needs to be done anytime you change tire sizes that are outside the parameter of the OEM and then link tha to the Mfg recommendations for PSI to weight.


Black is wet, white is dry, psi was 110 psi and I lowered it to 70-75 psi for street and hwy.

37x15:50x17 BFG KM2 16 psi, full contact patch, no bulging on sidewalls, drive perfect

F 450 Truck loaded out for travel

Typical Weight - PSI Mfg spec Product Data Guide, Contential Commerical tires I use on my F 450, circled in green is my tire size

Interesting comments but I am talking about stock 35s on the XR package. No tire change or size change. New Jeep.

 

[Byrds8]

Interesting comments but I am talking about stock 35s on the XR package. No tire change or size change. New Jeep.

He was just giving examples of how to ensure you get the correct PSI for the tire/vehicle combo. I personally run mine at about 33psi. They could be lower as they still do not have full contact.

 

[chicknwaffles]

He was just giving examples of how to ensure you get the correct PSI for the tire/vehicle combo. I personally run mine at about 33psi. They could be lower as they still do not have full contact.

33psi on a stock XR.


well guess I need to lower mine

 

[Byrds8]

33psi on a stock XR.


well guess I need to lower mine

I probably could get away with 30psi but just didnt feel right running down the interstate every day with them that low.

 

[chicknwaffles]

I probably could get away with 30psi but just didnt feel right running down the interstate every day with them that low.

i hear that. i'm at like 35-36 now

 

[Byrds8]

i hear that. i'm at like 35-36 now

I do not recall getting much worse MPG when I ran them at 31-32. I mean it sucks on the hwy as it is. Doing 75MPH back and forth to work I only get like 16ish. I get better in the city that I do out on the HWY lol.

 

[jonyothan]

i dont even have the xtreme recon package on mine but i noticed the same thing with the stock 285/70r17 ko2s. i run 33 psi and it drives waaaay better

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