Dodge RAM Cummins 24V Diesel
Dodge RAM 2500 Rubber Rims
Dodge Bent Wheel Problem
The 1998 Dodge Ram 2500 factory chrome plated steel wheels are exceedingly weak. They could best be described as "rubber rims." The wheels are a two piece design where the two main parts are welded together. The inner disk with the mounting lug bolt holes is stamped from plate steel. It acts like a diaphragm. The outer rim is the typical rolled and welded design onto which the tire is mounted. The assembly is chrome plated on the outside after final welding and polishing. The wheel has a very pleasant design with six oval shaped openings. Wheel weights can be attached to the outer rim on either side in the typical manner.Problem
The diaphragm or inner disk of the wheel is exceedingly weak. It doesn't break, crack, or fatigue; but it does flex, deform, and bend easily. The result is a tire that wobbles from axial run out of the outer rim. In other words, the centerline of the tire does not remain on the rotating center. This can easily be observed by jacking up both rear tires at the same time, blocking the front wheels, and running the truck at an idle in first gear. The tire tread wobbles in and out as the tire rotates.
The second symptoms is radial deformation or movement. The surface of the tire can be observed moving in an up and down manner as it rotates making the tire appear to be out of round. Axial center of the outer rim had defected from the centerline of the axle shaft.
The weak center disk of the Dodge wheel can easily bend from the impact load received as the truck passes over a railroad crossing that may be a little rougher than expected. The construction "bumps" commonly seen when highway repaving is being done will bend the rims. Sometimes the 2" to 3" temporary ramp is installed to reduce the bump but many times it has none. Ordinary chuck holes will also bend the Dodge rims.
The stress in the metal in the center disk of the Dodge wheel exceeds the yield strength during normal highway driving when typical rough road conditions are encountered, such as: railroad tracks, chuck holes, and construction irregularities. Off road conditions are even worse. The stress is at least three time the desired amount for a sound design. The stress should not exceed 1/3 to 1/4 of the yield stress. The stress is inversely proportional to the thickness of the metal to the power of 3. Therefore, the metal should be increased by the cube root of 3 = 1.44 or 144% (say 150%), proving that the metal is approximately two thirds the thick that it should be. Dodge did not perform the required engineering design on these wheels. Someone at Dodge simply let the accounting department guessed at the desired metal thickness. They then proceeded to make millions of them. This is a prime example exposing why the public does not have confidence in cars and trucks made in the United States.
A proper design would be to increase the metal thickness in the center disk by 1.6 times, reduce the size of the oval cutouts, and stamp the 3-D pattern with more emphasis to increase the sectional modulus. The additional cost to make excellent wheels would have been approximately $2 per wheel.
We see heavy duty truck advertisements on TV by Ford, Chevrolet, and GMC where the truck is heavily loaded and driven over very rough terrain at a construction site. We also see advertisements where the truck jumps obstacles with the wheels off the ground followed by a jarring impact that bottoms the suspension. The Dodge wheel would never even come close to surviving these severe loads. The Dodge wheel would be severely bent out of round and off center.
The Dodge wheels wobble and hop as the truck is driven on a smooth highway. This causes wear cups on the outer edge of the front tires and shortens the life of other suspension components. The rear tire are less likely to wear unevenly because of the more rigid back axle. Balancing the tires does not cure this problem, and the amount of balance weights required will be much greater than on an unbent wheel.
Crossing one rough railroad track with the truck empty or loaded can easily bend all four rims. The cost to straighten and rebalance the all four wheels will be between $700 to $1000. The entire repair could be reversed while driving home.
There are no permanent solutions to the weak Dodge rubber rims other than to buy better replacement wheels for an after-market source, not from Dodge. Buy wheels that are designed and tested for severe off-road racing.
Please give feedback if you discover other methods of resolving the Dodge factory rubber rim problem.
Kent R. Rieske, P.E.
Professional Mechanical Engineer
Automotive and Lubrication Specialist
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