One thing that generates a lot of discussion between M37 owners is tires.  Once I started driving my truck, it became apparent why this is a topic that is so passionately discussed.  The truck as I received it had four military non directional tires (NDT) mounted on it.  I also acquired a partial set of tires and wheels on the parts truck.   In looking at the tires, none of them was less than thirty-five years old.   They all had mild cracking over the entire surface due to age and they had hardened until they where like rocks.  They did hold air and they looked good from a distance...

Obviously, I needed to put new tires on the truck if I was going to drive it any appreciable amount. 

After a lot of thought into how I was going to use and modify the truck, I decided to stay with a tire that was pretty close to the original tire in size.  I also wanted a tire that would handle well in a variety of conditions since the state I live in stretches from the coast to mountains with soil types ranging from sand to clay to silt.  In addition to good performance off road and in inclement weather, I wanted a tire that would wear well on the road since I had to drive the truck to any place I where I wanted to play.

One weekend, while visiting friends of the family on their farm in Madison County, Virginia, I got to looking at the tires that the had on the farm vehicles.  One in particular intrigued me as it was a directional tire with two wavy center ribs flanked by beefy lugs running from the ribs to the sidewalk.  I noticed that this tread pattern was on a number of the trucks used in the orchards and for feeding cattle ranging from pickups to flatbeds. 

Upon asking my hosts about the tires on their vehicles, I found that they purchased them all at their local Southern States, the Orange-Madison Co-Op in Madison.

The very next day I headed down the road the co-op to talk tires.

When I got to the tire shop, I spotted what I wanted.  They had a huge stack of Grip-Spur tires that had a pair of center ribs with large lugs running from the ribs to the edge that had just a little angle to them, and they where non directional.  I asked the guy at the counter if they had any in a 900x16 since that is the size on the M37 and what was in the pile in the warehouse was all 7.50x16 (for Chevy's).  He told me that he had two of them in stock in a 900x16 that were left over from an order some Power Wagon owner had placed....  After getting both contact information for the other Dodge owner in the area, and a promise that he would see if he could get two or three more tires into the shop, I headed home.

After getting a call from the tire shop later that day informing me that they could get two more tires in the next week, I decided to demount my existing tires and paint my wheels before getting the new tires mounted.  I removed the wheels from my truck and took them to a local truck shop the following Saturday and had one of the more experienced tire guys demount the old rubber.  After watching him swing his sledge on the tires, I figured it was an absolute deal to have him do all the sweating...

I took everything home for sandblasting and painting.

A couple of weeks later, I went back to the Co-Op with my wheels loaded into the back of a friend's pickup.  After a short wait while they scrounged around for my tubes (they had put them in a safe location while they waited for me to get my wheels ready, but it took a while to remember where that safe location was located) the mounting was done.   The entire time that the two piece wheel specialist was working on my tires, he kept telling everyone what a joy it was to work on clean wheels.  After he had aired the tires up and helped me load them into my borrowed truck for the trip home, he made sure that I was not charged for his services, just for the tires, tubes, and flaps.

Once I got home and mounted the wheels back onto the M37 and went for a test ride, I was amazed at how much better the truck rode.  Although I did have the tires aired up to 50psi, it still felt like I was driving a Cadillac instead of a Mack...

Information stamped on the tires reveals a little bit about them, especially when you find a listing of DOT codes on a web page such as the one located at Harriger's.   This information should allow your local tire guy to find them using the DOT plant code information, if not, go to a better tire shop which you need to do anyway in order to get your two piece wheels worked upon.  Remember that you have two piece GY-LTS wheels that have a lock ring on a solid rim instead of split rims...

Information from the sidewall of my tires:

Co-Op Grip Spur 900x16
Load Range D Tube Type
Tread 6 Plies Nylon Sidewall 4 Plies Nylon Cord
Max Load Single 3030 lbs at 50 PSI Cold
Max Load Dual 2665 lbs at 50 PSI Cold
12908 ITS-3


We find that the plant code (PK) on my Grip Spurs reveals that my tires where made by the KELLY-SPRINGFIELD TIRE COMPANY (note that K-S is a wholly owned subsidiary of Goodyear these days) in the FREEPORT, ILLINOIS, plant.  The 516 tells us that my tires where made on the 51'st week of 1996 since the first two digits are the week in the year with the last one being the year.  If the tire code had been PJ instead of PK, I would be riding around on tires made at the Fayetteville, NC, plant located fifty miles from my current home...


One thing that can be said for these tires is that after they have warmed up a bit, and have become round, the ride is really good.  Offroad performance on the materials that I drive on (loose gravel, sand, loam, and mud) is pretty good.  Onroad performance at speed, especially in the rain, is great.  I've enjoyed these tires so much, and they have worn so little even after they have been on the truck a couple of years, that even when I got a set of Michelin 1100r16 XL radials as part of a large order I placed for a friend three years after I mounted the Grip-Spurs, I did not install my set on my truck.

Further discussion of the various tires used on the M37 series of trucks is continued on the next page.