Subaru WRX and STI Wheel Offset, Weight, and Fitment

What a Wheel Change Does

An aftermarket wheel is there for looks, for less rotating weight, or for a wider tire. There is no single best maker. Price, appearance, and how many pounds it saves against the wheel already on the car are the three splits that matter. Alloy recipes and construction methods are proprietary, and none of them has a result that settles the argument.

Ask the seller how returns work before you buy, and check the width and offset against the car in the table below. A calculator that compares offset to the stock wheel is the check. Clearing the fender is not that check.

Stock WRX and STI Wheels

The factory wheel on these years is strong, light for what it is, and finished well enough that a heavier aftermarket wheel is a step backward. Every row below uses a 12x1.25 stud, a 19 mm lug nut, and 65 ft-lb. The 2002–2005 WRX tire on this list is a Bridgestone Potenza RE92, 205/55R16.

One 2008 WRX wheel, weighed with the tire-pressure sensor and a light set of balance weights, came out at about 23.2 lb. That is one wheel, and it sits next to the 23 lb figure above. A 2008 STI BBS wheel was weighed at about 21 lb, against the 28 lb standard 2008 STI wheel. That 21 lb figure is one measured set.

Wheel Offset

Offset is the distance from the hub mounting face to the centerline of the wheel. A higher number moves the wheel in, toward the car. A lower number pushes it out. The wrong number wears suspension parts and body panels faster. A wheel that fits is not automatically the right wheel.

That chart and the factory wheels do not agree. A 7-inch 2006–2008 WRX wheel is +55 mm, above the +50 to +53 mm band. An 8-inch 2005–2007 STI wheel is +53 mm, well above +43 to +47 mm. For a tire and wheel that stay near stock size, use the offset on that car, not the chart. The “close” band on the chart is ±2 mm. Two inches is a different number, and it is not close.

Bolt Pattern and Lug Nuts

Pattern is the first filter. A 2005–2008 STI wheel is 5x114.3 and will not bolt to a 2002–2008 WRX or to a 2004 STI. Those cars are 5x100. A 2004 STI wheel is 5x100, so it shares the WRX pattern. Thread on every car in the table is 12x1.25.

Lug nuts differ by the shape of the seat, and there are three shapes. Most aftermarket wheels for these cars use a 60° taper, and that is the seat the factory nut clamps. A stock nut and an aftermarket nut interchange when both are that taper. A ball seat or a flat seat, the seats on VW and Mitsubishi wheels, will not clamp a 60° wheel, and a 60° nut will not clamp those wheels. Even with a matching taper, a thick shank can sit proud of the lug pocket. A slim socket is what gets a thick shank down onto the seat.

One factory wheel on these cars may have a locking nut. The matching key comes from the dealer when they can read the code on the nut. Splined nuts, where every nut on the wheel is the same special shape, take the socket from the company that made them.

• Deep-well 19 mm. Best grip, and it leaves room to swing a torque wrench.
• 3/4 inch. Fits, with a little more play. Three-quarters of an inch is 19.05 mm, about 0.002 inch larger than 19 mm.
• Standard socket. Reaches only about halfway down the nut, so it is the wrong tool.
• 3-inch extension. Keeps the wrench handle off the wheel face and off your knuckles.

Wheel Weight

A heavier wheel costs acceleration twice. The car has to move the extra pounds, and it has to spin them. An extra 5 lb at each corner, 20 lb in all, acts like about 50 to 80 lb added inside the car when you are trying to accelerate. The same pound also costs more when it sits farther from the hub. Spinning 1 lb at 9 inches from the center takes more work than spinning that pound at 8 inches, which is why a larger diameter raises rotating mass even when the scale weight does not change.

Unsprung weight is everything the springs do not hold up: control arms, brake parts, spindles, wheels, and tires. Less of it lets the suspension move faster and keeps the tire on the road over bumps. The cut that does not give up braking or suspension is the combined weight of the wheel and the tire.

A light 205/55R16, a T1S, weighs 21.2 lb. The RE92 on the early WRX is in the same range. Add the 16.5 lb WRX alloy and that corner is about 38 lb before you change anything. Weigh the new wheel and the new tire together, not the wheel alone. An 18-inch wheel can come in lighter than a 17-inch wheel when the overall tire circumference stays stock, because the shorter tire can drop more weight than the wheel added.

Wagon and Sedan Wheel Fitment

A sedan and a wagon do not share the same fender. The sedan’s flares can clear a wheel that rubs the wagon. Check the body you actually have, not a photo of the other one.

Wheel diameter by itself does not move the speedometer. Tire circumference does. Keep the rolling circumference close to the tire that came on the car if the speedometer has to stay honest. Compare the old tire and the new one before the tires are mounted.

Everyday driving does not require a V-rated tire. S-rated and above is the floor for ordinary use. The order runs S, T, U, H, then V, so an H-rated tire sits above that floor.

Balance and Installation

An out-of-balance wheel wears the tire and the suspension faster. A normal balance is enough for most cars: weights cancel small differences in weight around the tire. Where those weights go — face, inner barrel, or tape in the middle — is the machine’s call. Say so before the work starts. A shop will often hide the weights on an aftermarket wheel unless you tell them to follow the machine.

If the shake is still there after that balance, the tire’s springiness under load can be the cause. That radial-force variation is not a high spot or a low spot you can see on a wheel sitting on the floor. The tire has to be pressed against a roller while it spins, the way a loaded balance machine does it, and the weights are placed from that reading. It costs more than a standard balance, and it is the step for a vibration the first balance did not fix.

Plan on about an hour. Follow the wheel maker’s steps when they exist. When they do not, use this order and set every nut to 65 ft-lb with a torque wrench.

1. Seat the wheel. Finger-tighten the nuts so the wheel is centered on the hub and not rocking in the lug holes.
2. Snug by hand. A thin-wall socket and a short extension, turned by hand, pulls the wheel up without the wrench scraping the face.
3. Torque to 65 ft-lb. Deep-well 19 mm and a 3-inch extension. That is the torque for every car in the stock table.

FAQ

Does wheel fitment change the speedometer?

A larger wheel does not. A tire with a different circumference does. Compare the old tire and the new one before they are mounted.

Will 2005 STI wheels bolt onto a 2002 WRX?

No. Those STI wheels are 5x114.3. The 2002 WRX is 5x100. A 2004 STI wheel is 5x100 and shares that pattern.

If the wheel clears the fender, is the offset right?

No. Offset outside the range for that car loads the hub and the wheel bearing. Match the offset on the car when the tire stays near stock.

Do I need new lug nuts?

Only when the seat does not match. These cars use a 60° taper. Keep the factory nuts for the spare if the new nuts are different.

What socket fits the lug nuts?

A deep-well 19 mm, with a 3-inch extension. A 3/4 inch socket fits with a little more play.

Do I need V-rated tires for daily driving?

No. S-rated and above is enough for ordinary driving. H sits above that floor. V is not required.