Repeat the process on the...
Repeat the process on the rear of the car. Again, remember to compress the suspension to approximate ride height, account for suspension travel, and watch for obstacles on the inside.
Size Does Matter
* When measuring for wheel sizes, remember to account for the tire's height and width. Tire dimensions like overall height and section width are usually available from the tire manufacturer.
* Just because a particular wheel-and-tire combination fits your buddy's Chevelle street machine does not mean it will automatically fit your Chevelle, too. Never assume that it will. Instead, take measurements for yourself or trial-fit the wheels and tires on your car.
* In addition to checking clearance between the rolling stock and outer sheetmetal, check the inner side of the wheel and tire. Make sure they aren't hitting suspension components, the inner wheel housing, or the frame, even when the steering is turned to full lock.
* Remember that tires will flex and expand during cornering and other normal driving conditions. Don't cut clearances so close that the tires will begin rubbing the first time you roll over a pebble in the road.
* Disc brake conversion kits, dropped spindles, tubular control arms, and other aftermarket suspension components can alter the track width of your front suspension, which will affect tire and wheel clearance. Keep this in mind when planning modifications or selecting wheels and tires.
* On a similar note, if you're planning to lower your car or perform other suspension modifications, we suggest making those changes before ordering new wheels and tires.
This handy tool from Percy's...
This handy tool from Percy's High Performance can take a lot of the guesswork out of measuring for wheels and tires. It lets you select a diameter and width (with varying backspacing), then bolt the fixture to your brakes and see if it's going to hit anything.
* If you're using extra-large aftermarket brake rotors and performance calipers, make sure they will work with the wheel size and design you choose.
* Always take wheel and tire measurements with the suspension compressed to approximate ride height.
* When in doubt, it's best to err on the side of caution. You can always use a set of wheels and tires that are a little narrower than what you wanted, but it can be difficult or impossible to drive a car with rolling stock that's too wide.
* Trial-fit any new set of wheels you get before having the tires mounted. Wheel manufacturers and retailers will often let you return or exchange wheels that haven't been mounted yet.
* When using wheels with different offsets, diameters, or widths for front and rear, you may encounter difficulty should a flat occur. It's wise to choose a spare that will fit both the front and rear.
* Big openings in large-diameter wheels will leave puny (or dirty) brakes exposed. One way to conceal such unsightly items is to use wheel inserts like those available from Air Ride Technologies.
* Unique (and especially large) tires may prove hard to locate- especially in smaller towns or while on the road. Take this into consideration before deciding on those 20-inch rims and 395/25ZR20 tires.
 It's designed (and priced)...  It's designed (and priced) for shops that need to measure wheels on a regular basis, but if you get creative you could easily make something at home that would serve the same purpose. Note how a piece of wire represents the added width and height of the tire. |  No matter how much measuring...  No matter how much measuring you do, nothing beats being able to trial-fit wheels before you buy them. If they don't clear (or are very close), there's no chance a set of mounted tires will. If you get your wheels via mail order, always remember to trial-fit them before mounting the tires. Wheel manufacturers will often let you exchange wheels that haven't been mounted. |  If you measure carefully and...  If you measure carefully and correctly, you'll be le to stuff the maximum amount of rubber under your ride while keeping it all inside the wheelwell lip. |