This is a question we get all the time: “How big a tire can I mount on my (fill in the blank).” It’s not such an easy question to answer, as there are a number of factors that can effect what size tire will fit on a truck, especially a stock rig with no lift kit. For one thing not all brands and types of tires are exactly the same diameter and width even if they are called out as the same size tire.

Differences in manufacturing techniques can create variations that can mean one LT285/10.50R17 may rub on a steering component when the steering system is turned to full lock while another LT285/10.50R17 will not. Wheel backspacing has a great deal to do with this equation as well. Often times it’s a matter of trail and error, which is not always a great way to go about this sort of decision.

Your best strategy is check out as many resources as possible before making that decision. Those may include the tire manufacturer, vehicle manufacturer, tire shops with a long history of mounting wheel and tire combinations on trucks, and as we have found lately, specific make and model forums.

While searching for information such as this, we came across some the experiences one truck owner chronicled on the Cummins Forum that we thought would be educational for a number of Diesel Army readers. Cummins Forum member NT2HLBLY owns a stock 2008 Ram pickup and has spent a goodly amount of time working on the solution to just how big a tire he can mount up.

As you can see from the photos, he was able to mount up 37-inch tires. As NT2HLBLY puts it, “Well here it is, the hit and miss pics. On a 2008 with NO lift/level mounted on stock rims. The tire is a Goodyear Wrangler 37×12.50R17LT MT/R.” However he does admit, “The passenger side control arms rub the same on or off road but not really that bad. The driver side just barely touches. No fender rubbing front or rear.”

So it would seem that a 37×10.50R17 would likely fill the wheelwell on a stock Ram just as well, and probably not create any interference with the control arms. Stay tuned to Diesel Army for the latest news, events, and tech in the diesel world, and more tips on tires! If you have more tire fitment tips to pass along to Diesel Army readers, feel free to share that information in the Comments section below.