Dear Top Gear,
Will the tires rub on the wheel well of my 2009 Ford Escape XLT if I upgraded to 20-inch rims? I originally wanted 18-inch rims but the shop insists 20s look much better (and they do). My concern, however, is the handling of the vehicle.
Hi, Cali Boy!
Your factory tire size is specified to be 215/70-R16, meaning it's got a tread width of 205mm with a 70 aspect ratio (or sidewall height that's 70 percent of your tread width) mounted on a 16-inch wheel. You'll want to keep these numbers in mind when choosing a new wheel and tire combination. These numbers also mean your factory tires' current outside diameter is about 27.85 inches. Keep that number in mind because you don't want to stray too far from that.
Using a 235/50-18 for example--if such a tire size exists--will give you an outside diameter of 27.25 inches, while a 235/55-18 will give you a tire that's theoretically 28.17 inches in diameter. Now either size will be under two percent bigger or smaller than stock and, as far as diameter goes, is acceptable since it won't affect your final drive ratio much.
As a rule of thumb, a smaller tire diameter will give you better acceleration and lower top speed while a bigger outside tire diameter will give you slower acceleration with slightly higher top speed, depending on your engine's capability. In both instances handling will improve slightly because of the increased tire width.
What you have to watch are the wheel offset and wheel width--which determine whether or not your new wheel and tire combination will rub against the fender wells. If the new wheel width is too wide, you will need one with an offset that locates the wheels further outwards to prevent rubbing the inner fender with the new tires. It's a double-edged sword since with an offset that locates the wheels too far out you may end up with the wheel rubbing on the outer fenders of the vehicle.
Personally, I would not go with a too large a wheel as it adds a bit of load onto the suspension components than necessary resulting in accelerated wear--unless the new wheel and tire package's overall weight are not significantly higher (anything more than ten percent) than the factory wheels they are replacing.