Off Roading Cooper Discoverer STT Pro Tires

[CVR222NV]

I have been running Toyo M-55's for a couple of years without any problems but over the last six weeks have lost 3 tires, one by punctured sidewall and two blowouts at low speed (30 mph) on county maintained gravel roads. The two blowouts were total sidewall separation but that could have been from running them on the rim until I got the truck stopped. Discount Tire thought I had somehow lost pressure. Given the price of the Toyo M-55's I went with the full warranty which Discount Tire has honored. I now have 4 new Toyo M-55's all around but have lost confidence in them for off road use. I had heard good reports on the Cooper Discoverer STT Pro with the beefed up sidewall protection. Just wondering if anyone has had experience with these tires or have any other suggestions?

 

[bigceltic]

I have been running Toyo M-55's for a couple of years without any problems but over the last six weeks have lost 3 tires, one by punctured sidewall and two blowouts at low speed (30 mph) on county maintained gravel roads. The two blowouts were total sidewall separation but that could have been from running them on the rim until I got the truck stopped. Discount Tire thought I had somehow lost pressure. Given the price of the Toyo M-55's I went with the full warranty which Discount Tire has honored. I now have 4 new Toyo M-55's all around but have lost confidence in them for off road use. I had heard good reports on the Cooper Discoverer STT Pro with the beefed up sidewall protection. Just wondering if anyone has had experience with these tires or have any other suggestions?

I ran the STT Pros for the last few years and really liked them. My only issue was they were a bit too loud for me - mind you, for a mud tire, they are relatively quiet but they were a mud tire! Great for towing (I ran 80psi all round when towing), fantastic in the rain and snow, great for the minor off roading I have done. I will dig up my receipts to find out what kind of mileage I got, as I just replaced them on Saturday. If you don't mind the noise (and it really wasn't that bad - let's put it this way, my wife never complained) these are great tires.

Update: I had the STT Pros put on in Apr of 16 and ran them for 30,967 miles, lots of towing, and they still had some tread left - if it were the summer, I prob would have run them for a few more months.

 

[GrantP]

I abuse my Nitto Terra Grappler's off road at ludicrous speeds in rough terrain. Zero issues with them and they are quiet on the highway and are wearing well. They aren't a good tire for mud though, it's an AT tire. Bonus: They're made in the USA, Coopers probably are too.

 

[KATOOM]

If you liked the M-55's then you'll probably want to look into Coopers S/T MAXX. Similar hybrid mud/AT style tire and they're quiet.

 

[CVR222NV]

If you liked the M-55's then you'll probably want to look into Coopers S/T MAXX. Similar hybrid mud/AT style tire and they're quiet.

If I were starting over again this would probably be my choice because this tire has the 3 ply side wall design. However, I have virtually new Toyo M-55's that I need to run out. I'm thinking of running two sets of tires at this point. The Toyo's from January to July and a mud tire from August through December when I do most of my off-roading.

I abuse my Nitto Terra Grappler's off road at ludicrous speeds in rough terrain. Zero issues with them and they are quiet on the highway and are wearing well. They aren't a good tire for mud though, it's an AT tire. Bonus: They're made in the USA, Coopers probably are too.

Nitto was the other tire I was considering but in the Trail Grappler or Mud Grappler due to the 3 ply side wall. The Mud Grappler has steel belts as well.

The Toyo M-55's are 28570R17. I was thinking of bumping up to 28575R17 for a little taller tire. I think that would be my limit and still be able to get the truck in my garage. I can get that size in the Cooper S/T Maxx but not the STT Pro. Bummer!

 

[GrantP]

If it helps, I'm running 37's and the truck still fits in my garage with a typical 7' door.

 

[Tuesdak]

Is it the shadow or is the rim bent in the picture? It appears to line up with "impact damage" on the tire itself like the cracking at the sidewall bead. How far did you run on the rim - just to come to a stop or a safe place to stop?

 

[jhenderson]

It sure looks bent to me.

 

[Regcabguy]

I abuse my Nitto Terra Grappler's off road at ludicrous speeds in rough terrain. Zero issues with them and they are quiet on the highway and are wearing well. They aren't a good tire for mud though, it's an AT tire. Bonus: They're made in the USA, Coopers probably are too.

They are nice but I wish they had the Nitto Ridge Grappler's stronger sidewall. I had M-55's on my old truck and had zero issues with them. Coming out of BFG KO's they were heaven sent. The oil field guys seem to like them.

 

[GrantP]

Coming out of BFG KO's they were heaven sent.

We're in total agreement on that, anything but BFG's for me now.

 

[CVR222NV]

If it helps, I'm running 37's and the truck still fits in my garage with a typical 7' door.

With wood trim my garage door opening is 82 1/2". When I added the bumper and winch I upgraded the front springs which as I recall added 1 1/2". Add to that I have a radio antenna on the top of the cab. I monitor my truck height pretty close.

Is it the shadow or is the rim bent in the picture? It appears to line up with "impact damage" on the tire itself like the cracking at the sidewall bead. How far did you run on the rim - just to come to a stop or a safe place to stop?

No shadow the rim was bent. I was on a county maintained dirt road that gets rough from use until the County can blade it periodically. On the tire in the photo I was going around 30 mph when the truck started shaking violently before I realized what was happening and stopped. Too late apparently. Nothing I did would have caused the bent rim other than running the truck on the flat tire. Discount believes the damage to the tire and rim was likely caused by driving on the flat after the tire lost pressure.

On the third flat the truck again started to shake but I was a little quicker to realize what was happening so got the truck stopped quicker. Rim was not bent but it was cracked! I checked the other tires and wheels on the truck and found another cracked wheel. I had a violent event a few years ago where I hit a wash out in the road going 45-50 mph. I'm thinking the bent rims were on the front when I hit the wash out. It was such a violent hit that it killed the engine and bent the front axle. I had Discount swap out all steel wheels for 5 spoke aluminum OEM wheels I had purchased off Craigslist.

They are nice but I wish they had the Nitto Ridge Grappler's stronger sidewall. I had M-55's on my old truck and had zero issues with them. Coming out of BFG KO's they were heaven sent. The oil field guys seem to like them.

I made it through the end of the 2017 hunting season and all of the 2018 hunting season without a flat using the Toyo M-55's which was much better that when I was running the Hankooks. I can't point to anything I have been doing different this year over last year. I'm consistently rough on tires so I'm looking for a tougher constructed tire with the beefed up sidewalls to see if that helps.

 

[bigceltic]

I think you will be very happy with the STT Pros.

 

[AEdelheit]

They are nice but I wish they had the Nitto Ridge Grappler's stronger sidewall. I had M-55's on my old truck and had zero issues with them. Coming out of BFG KO's they were heaven sent. The oil field guys seem to like them.

I have Nitto Ridge Grapplers and the sidewalls feel just as strong as the Toyo MTs they replaced.

 

[Tuesdak]

Were the tires actually replaced after the "violent event a few years ago"?

Regardless I was thinking it's impact damage causing the failures as it lacks a lot of 'driven a ways flat' telltale failure signs. As you drove on the rims off road with a flat that could bend them up as well.

http://www.rvtiresafety.net/2012/12/impact-damage-or-defective-tire-how-can.html

 

[CVR222NV]

I was running the Hankooks at that time and they survived the impact but I had many flats on those tires so eventually went with the Toyo M-55s. The Toyo’s had many stress events that could have damaged the tires with delayed impact. I have no evidence that the Toyo’s were defective. I’m just believe they are not constructed tough enough for what I put them through. I’m thinking the two ply sidewalls might be the weak link. The reason I believe the rims with the cracks were from the prior violent event is one of the rims that did not have a blow out was cracked. However the last blowout I had my RZR on the flatbed and it probably weighs 1400 - 1500 lbs.

 

[JR]

Given the tread designs you are looking at and have previously used the AT3 XLT are likely not aggressive enough for you but so far I am thoroughly impressed with their traction abilities. Vegas likely does not have alot of mud so they would probably serve you well. Previous tire on this truck was Cooper S/T Max installed by the previous owner within 2k miles of selling. Every pace I have put the XLT through in 8 months of ownership I put the Max through many times over in 3 years and the XLT have been superior. Light mud, snow, unimproved roads, lease roads, soft ground, towing, etc.

The problem with the Max was after a summer of towing they were so hard they lost most of their attributes. And I'm only in northern Ohio where temps are doing good to break the 90's 15 days out of the year.

 

[CVR222NV]

Given the tread designs you are looking at and have previously used the AT3 XLT are likely not aggressive enough for you but so far I am thoroughly impressed with their traction abilities. Vegas likely does not have alot of mud so they would probably serve you well. Previous tire on this truck was Cooper S/T Max installed by the previous owner within 2k miles of selling. Every pace I have put the XLT through in 8 months of ownership I put the Max through many times over in 3 years and the XLT have been superior. Light mud, snow, unimproved roads, lease roads, soft ground, towing, etc.

The problem with the Max was after a summer of towing they were so hard they lost most of their attributes. And I'm only in northern Ohio where temps are doing good to break the 90's 15 days out of the year.

JR, you are correct that Southern Nevada is a rock pile and the higher elevations where our ranch is located is also very rocky. However, the roads in the valley floor turn into silt beds from lack of precipitation which is the current state since we have had very little rain since June. When the rains come that silt turns to horrible slick mud so we have to deal with mud as well. The ranch is at 6400 ft elevation and during winter we have snow and at times lots of it. Enough to have to chain up all four corners. For that reason the more aggressive tread would probably be better because I hate putting on chains! But I believe my issue goes beyond traction. I'm convinced that tire construction is my main issue hence the search for beefier sidewalls. The S/T Maxx and the STT Pro have their Armor Tek3 construction (3 ply sidewall). Certain of the Nitto tires have three ply sidewalls as well as do the Toyo's. That's the direction I'm leaning.

I do note that one of the ranch trucks has the AT3 LT's and they have held up well in daily use on the ranch but they are on a baby Ford and not a one ton.

 

[16longhorn]

I had nitto ridge grapplers. tried the stt pro afterwards. I wish I bought the ridge grapplers again. They are WAY quieter than the stt pros! I also feel that the stt pros aren't going to last as long. The ridge grapplers threw less rocks as well.

I'm a equipment operator on pipelines and I put the tires on asphalt (mostly highway), mud and rocks. The Nittos and the STT Pros did a great job in all those situations.

 

[MMcCallie]

The Toyo M/Ts are likely your toughest option. They are very expensive, heavy, and tread life isn't great but I've never run a tire so tough and reliable. I grossed 30,000 lbs towing to Alaska and back and cracked every wheel and did some tough off-roading with them. But I think my next tires will be the STT Pro for longer tread life and lower pricing.

If the AT3 were available in my size that would be my first choice. We've run a couple sets on other vehicles and they do not disappoint.

 

[CVR222NV]

The Toyo M/Ts are likely your toughest option. They are very expensive, heavy, and tread life isn't great but I've never run a tire so tough and reliable. I grossed 30,000 lbs towing to Alaska and back and cracked every wheel and did some tough off-roading with them. But I think my next tires will be the STT Pro for longer tread life and lower pricing.

If the AT3 were available in my size that would be my first choice. We've run a couple sets on other vehicles and they do not disappoint.

The Toyo Open County M/T is what my brother runs and he swears by them. They have the 3-ply sidewall that I'm looking for. His truck is used mostly on dirt roads and while he has not experienced the flats as I have the soft rubber and the gravel roads cause the tires to wear fast.