One of the most frequently asked questions by midsize SUV owners is what would be the proper tire size to put on their ride. Let me try to answer this for everyone based on the most common objective with regard to what they want on their vehicle.
The badass look. If this is the objective and the budget is as tall as the look you want to achieve, buy the tallest aftermarket lift kit for your ride available. This would be in the range of four to six inches, and install at least a 35-inch-tall tire. These huge knurly tires will bring fear to the most intrepid PUV drivers who snake through traffic with the thought of you tearing their fender or bumper off. Obviously, floodwaters (to an extent) will no longer be an issue for this tire size. Be warned: Those who still have warranties on their vehicle can kiss it goodbye.
Without voiding the warranty. For those who feel that their stock tire is a bit small but don't want to void the warranty, midsize SUV wheel wells are usually large enough to take on tires up to 32 inches in diameter. If your ride is equipped with electronic stability or traction control, your dealer can calibrate the system to your uprated tire size. This size range also gives the least amount of strain and stress on your vehicle's drivetrain (axles, CV joints, cross joints, transmission, transfer case, etc.) and should not void your vehicle warranty.
Performance and reliability. Do you have no qualms about your warranty? First, look at your vehicle through a 'bell curve' performance chart. As your tire size gets taller, your SUV's performance starts to suffer because of the added unsprung weight of a larger tire and the additional friction it generates. This causes a downward direction in the performance curve and the durability of your driveline components. Competent off-road shops should be able to advise you on this when you want to make the mods on your vehicle. If not, run away because they just want to make a sale and take your money.
Keep it real. I'm assuming that if you're upsizing your tire, it means your vehicle is a true 4WD and not a crossover or a 2WD. If your intent is just a taller tire for flood waters, 2WD SUVs with tall tires may even cause you trouble because the larger diameter will lessen torque, lowering its ability to push the weight of water out its way. Do remember that a square meter of water will weigh in at about a thousand pounds. That’s a lot of weight to push.
Natural high. If additional ground clearance is the objective, then you may be treading on ground that only a 4WD vehicle should be getting into. Play it safe, avoid the inconvenience of getting the vehicle high-centered (this means the SUV is stuck on a tall obstacle) and not being able to drive away. In most cases, even 4WD vehicles get high-centered, becoming immobile without being winched or towed out.
In closing, if looks and stance is all you want to achieve, then by all means go for your desired look. Just let it be said here that you have been warned.