Wheel Works Tool - Mount Up

The Mount Mate can be ordered with a mounting flange to accommodate any axle from four to eight lugs. Its heavy-duty, cast-aluminum construction allows for mounting any size tire and simulating its bulge on the road with a little bit of suspension down force.

These photos show what changes in width-from a 225 to a 235 to a 245-will do to fender clearance. Each tire was checked using the same settings on the Mount Mate.

These photos illustrate the difference even a minor change in size can create. Both tires are Falken Ziex ZE-502s; the front tire is a 245/50R16 and the rear is a 235/55R16. The 245 tire is 9.64 inches wide by 25.65 inches tall. The 235 tire is 5/8 inch narrower (9.25 inches wide) and about 1/2 taller (26.18 inches) but looks much skinnier and taller when compared side-by-side.

Pictured here are the three tires we checked on our vehicle using the Mount Mate. Left to right are: 225/60R16, 235/55R16, and 245/50R16. We went up one size in width (10mm) and down a half-point in aspect ratio with each tire.

Cut a straight piece of wood to fit across the wheel flange and measure to the mounting surface as shown to find the offset of a wheel with a tire mounted on it. This wheel has a 5 7/8-inch positive offset.

Before ordering your next wheels, find out if they're listed by overall width or by distance between mounting bead flanges. The Center Line wheel shown here is listed as an 8-incher in the catalog, but if you mistakenly measured its overall width, you'd call it 9 inches. The Mount Mate is calibrated to determine mounting bead position, not overall width.

Backspacing (offset) can be confusing. This 17x8-inch Center Line wheel has an outside width of 9 inches and 0 offset, meaning the mounting flange is right in the middle. The manufacturer of this wheel measures offset from the outermost portion of the wheel flange, so it has a 4.5-inch backspacing. If the flange were moved out towards the street side, it would have a positive offset. Towards the inside means negative offset.

Ultra-high-performance custom wheels can be ordered "hub-centric." That means that the wheel center is custom-machined to fit exactly over the hub on your brakes or axle. That way, your wheel is mounted concentric to the axle centerline, not relying on the studs and lug nuts to locate it.

It's best to use stick-on weights in the center as shown, but this may hit the brake calipers. If so, move them to the outside edge of the wheel and cover them with duct tape when racing. Clamp-on weights can fly off at high speed, and they damage wheels when installed, so don't use them.

Steel valve stems are a good idea and usually a requirement in most forms of motor sports. When having your tires mounted, insist on new steel valve stems to replace the flimsy rubber ones.

Keep a stock set of lug nuts in the glovebox for your spare tire. Pictured left to right are: closed- and open-end Acorn-style nuts, long- and short-shank mag wheel nuts, and long- and short-shank open-end mag wheel nuts to fit over long studs used for drag racing. Upper left is a locking lug nut and key from McGard (716/662-8980, www.mcgard.com).

Traction is what it's all about and there are many chemicals on the market to help you get it. Some, like VHT's Track Bite, get poured onto the track before or sprayed on the tire during the burnout; others, like the Drag Racing Tire Treatment from Pro-Blend (800/331-9520, www.pro-blend.com) or Track Claw (800/638-7245, www.trackclaw.com) from Brothers Research, can be applied days prior to the race to improve tire adhesion.

After installing some trick leaf springs on this '70 Camaro ("Spring Back," Apr. '01), many people asked how we fit the huge 315/35ZR17 tires under the stock sheetmetal? Backspacing is the key and the 17x11 Weld Racing Type 76 wheels had 6 inches of it.

Tie rod and upper control arm/ball joint clearance can become an issue with deep-offset wheels in front. Pictured is our '70 Camaro's 17x9.5 Weld wheel with 6-inch backspacing to fit a 275/40ZR17 tire up front. See how the tie rod actually rides inside the wheel. If it were a 16-inch-diameter wheel, the tie rod would hit.