MPT80/81 Tires on Rubicon Unlimited?

Haf-E

Expedition Leader
I just looked up the MPT81's on Expedition-Imports website - it says they are rated for 68 MPH so that should be fast enough.

https://expedition-imports.com/0574005

The MPT 81 is the most common tire purchased for customers that spend a good amount of time on-road as well as off-road. These tires are quiet at speed, offer low rolling resistance, and do excellent in Sand, Snow, and the Rocks. In extreme mud the MPT 81 tends to have a hard time clearing itself and the MPT 80 is probably a better option. The MPT 81 is a direct competitor to the Michelin XZL.

275/80R20 MPT 81 Technical Specs:

Height 37.4" Tall
Width 10.43"
Speed rated for 68 MPH
Max load rating is 4674 Lbs at 77PSI.
Preferred rim is 9" Wide.
For more detailed specifications reference the Technical Data Book.
 

aarcher

New member
Hey Everyone!

Sorry this took a while. I got the tires on Monday. While driving to pick up the new tires the sidewall of my left front km2's gave out after a weekend of wheeling on it.

IMG_20170814_102147.jpgIMG_20170814_102159.jpg

These tires are HEAVY!! Nursing the jeep back home with the sidewall in that condition top loaded was not fun.

The next task was getting them mounted. I am running beadlocks so this is always a task as most shops wont touch them so essentially I'm usually on my own. Luckily a couple friends and wheel house pitched in to get it done. You can see here one of the MPT81's while the jeep is sitting on 37" KM2's. I got the Continental MPT 81 - 335/80 R 20 - (12.5R20) Air'ed up they measure just a hair under 41".

IMG_20170814_135013.jpgIMG_20170815_214519.jpg

The tires surprisingly did not rub at flex ( I had already trimmed my pinch seam) but they were very close. So I decided to completely remove the pinch seam and give it an extra 1.5" of clearance encase I suck something up into the wheel well.

IMG_20170815_224846.jpg

Mounting the tires took 5 hours (beadlocks). The bead on the tire is almost 1" thick. getting them on the front beadlock was extreamly difficult as the tire is pretty stiff.

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aarcher

New member
And the result:
IMG_20170816_182935 (2).jpg

for those that are concerned about the sidewall flex I set the tire on a jack stand at 15 PSI ( I usually run 5-8 when on trails) and this is what they did:

IMG_20170815_214835 (2).jpg

At 15 psi I was very impressed with the sidwall and tire contact patch flex. This ability is actually something continental points out on the MPT81 webpage.

Of course we had to go test the tires out that night:

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Initial review of the tires:

Test @ 30 psi on highway between 40 - 75 mph

There is almost ZERO road noise, I actually could not believe it. I almost should make a youtube video so you guys can (or can't hear it). I never thought a jeep this modified could be quiet. Literally I had the window down and the tires of the passenger cars next to me were generating more road noise. Maybe its because they are spinning much slower? I'm not sure but I love it!! Music on the stereo actually sounds good again.

They are INCREDIBLY smooth (used 20oz of beads per tire for balancing). The tall sidewall allows them to just soak up bumps and vibrations but with the thick ply they are not squishy and don't roll in corners. They handle great and corner well.

Considering this is my daily driver, I am much happier with the MPT81's then the KM2's I had. And I thought the KM2's were great.

Test @ 10 psi off road

At first you are going to feel really tall. This took a minute to get used to but it goes away. The tire aired down great and the sidewalls collapsed nicely, they sat very similar to my KM2's.
The trail we went on had moguls ~18" deep, a couple steep climbs up sand, climbs up sharp rock with small ledges(~20" tall). The tires almost had too much traction (The trail was sad and weak though so yea). I actually got out at one point and unlocked my front hubs so I could be 2wd in low. The tires completely conformed to every rock I went over and I didn't experience any slippage. I'm probably going out tomorrow again and would like to go down lower in psi to see what they do around 6-8.


Overall this is now the only tire I'm going to buy. The sidewalls are so strong with the 8 ply that I won't have to be buying a new tire every couple weeks.

Notes:

Don't try to run these tires unless you have Dana60's with 5.38's or better and Hydro Assist. you WILL break something (experience from destroying built up dana44's before). These tires get a ridiculous amount of traction. If you have anything less than that the only thing that is going to give is your axle and these will break it.

I will be taking the rig riding on these tires for a 3 week road trip up California and ending through the Rubicon trail so we will really get to see how they do with the highway/offroad combo.

I will try to update here about how the MPT81's do, but if your really interested I update Instagram daily with the project and you can follow me @adventureofandrew

If you have any questions ask away.
 
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Theoretician

Adventurer
Thanks for the update and initial review. I look forward to hearing about your longer term experience with those tires - I'll be shopping for tires in about 20k miles and I'm really tempted to figure out how to stuff the 37in version under my f150 without screwing with the suspension.
 

aarcher

New member
Hey Emkay,

The 20" beadlocks on the truck right now are Trail Ready. I also have a set of spyderlock beadlocks in 20" too. I actually prefer the spyderlocks better because the ring has more support. Unfortunately when I switched axles the backspacing of the spyderlocks didn't work well.
 

AggieOE

Trying to escape the city
That looks awesome! And I'm glad to hear they're actually working out for you so far. Definitely a unique set-up!
 

aarcher

New member
5,000 Mile Update!

Hey everyone!

So I wanted to update you on the MPT 81's on my jeep. Since installing them I have put on just under 5,000 miles. I have put the tires through some of the worst conditions possible:

I purposely pushed past their speed limit as that was a big concern for a lot of people. I ran them at 85 mph on the highway for 4 hours through the desert. The outdoor ambient temp was ~102 degrees tire pressure started at 37 psi and rose to 45. This is probably the worst thing you could do to tires. The MPT 81's showed no signs of fatigue or rubber degradation. They became warm but I could easily touch them, they did not seem hot.

I took them through the Rubicon trial. The other vehicle with me was running general grabbers. By the end of the trail his tires were completely chewed up and one went flat during the trail. He was also having a lot of traction issues. I aired the MPT 81's down to about ~8 PSI. The tires became extremely flexible and were not just grippy, but It was as if the vehicle just stuck to anything. I did every obstacle with no bypasses and the tires hooked up every time I needed them. At the end of the trail they had no damage. Surprisingly they still looked new. My beadlock rings suffered considerable damage with deep gouges out of the metal but there were no cuts in the sidewalls or chunks missing from the cleats on the tires as I experienced with my KM2's.

After 5,000 miles of trail and highway they are still as smooth and quiet as when I put them on. I took a decibel reading in the cab @75mph and It was between 68-70 decibels. My friend in a 4 runner with the general grabbers decibel reading in the cab was 80-82 decibels. If I remember correctly my KM2's were 76-78 decibels in the cab.

That's the latest and I'l update this in a coupe more thousand miles. I post regular pictures of them in use on my Instagram and also answer questions there if you have any.

Until then, I'll be out exploring!
 

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