So, you're wondering if you can fit those 44-inch Boggers under your new Avalanche? Well, no, you can't. But if you want to stuff 33-inchers under there, we may be able to help. Figuring out what tires fit under what vehicle is not an exact science, and anyone who tells you it is should have his psi checked. Truth is, there are so many factors that go into a tire's real-world height and clearance--air pressure, spring, shock and bushing condition, among them--that no one can tell you definitively if a big set of shoes will fit your four-wheeler's feet, unless you're performing the install yourself. Then, trust us, you'll find out soon enough.
The chart offered here lists what modifications, such as fender trimming or body and lift kits, are required to fit a certain tire size under a specific vehicle. Keep in mind that that doesn't necessarily mean such a body/lift kit is available for your truck. Another consideration: tire width plays a huge part in whether a tire will fit or not. A 33x12.50 may fit your '75 F-250, but you can bet you'll have a tougher time with a 33x14.50 tire. In addition, many newer trucks require proper wheel offset. This is critical because the standard offset on newer vehicles is more positive than on older rigs.
Here also is a chart that should help you figure out the height, in inches, of those dang metric tires that you almost have to be European to understand. Finally, another priceless resource presented here is our gear-ratio-to-tire-size chart, which tells you what gearing you'll need to retain your rig's final, overall gear ratio--or at least close to it.