How can I tell if a wheel will fit my car and clear my brakes?

If you are looking for a new set of wheels for your car, there are a lot of things to consider. You want to like the way the look certainly, and you also want to make sure that they will fit your car. If you aren’t straying from the factory wheel size, this is usually not very difficult. But if you want to put on a wheel that is larger than stock, things start to get complicated quickly.

If you are wanting to put on a wider wheel, you have to consider clearance for your suspension, and your fenders. Fortunately, there are a number of sites that can help you with this, and in terms of fender clearance, if you are willing to modify them, rolling your fenders can help you with clearance there as well.

The best wheel and tire calculator that we have found is this one:

https://www.rimsntires.com/specspro.jsp

But there is one other aspect of wheel fitment that often gets overlooked, and that is brakes. If your wheel is going to fit, it has to clear your calipers too, and it turns out that this is a lot harder to calculate for.

If you are staying with stock calipers, again, this will be easier because if you can find any site that has test fit wheels, then you know that they will clear. If you are putting on larger calipers, such as putting on Subaru 4-Pots or STI Brembo’s that came on a similar car onto your WRX say, there is a handy trick that you can use. You simply look up wheels for the car that came with those brakes originally, and pick something that will fit that car. In the case of the STI, if you have a 2002 – 2007 WRX, you need to look at the 2004 STI only, because of bolt pattern.

The other thing that you need to know here is that if you are looking at cast wheels, the spoke shape of the wheel will change with nearly every different width of wheel. So if an 8” wide wheel clears a caliper, don’t assume that an 8.5” or 9” wide wheel will. The perfect example here is the Enkei RPF1. They make a 17X8” wheel that is designed to clear STI Brembo calipers, and it fits with tons of clearance. But the 17X9” RPF1 doesn’t even come close. These are the wheels that we are currently running on our Pikes Peak WRX and we needed a 15mm wheel spacer to get 17X9” et 42 RPF1’s to clear the 328mm Stoptech Brake kit.

But if you are putting on an aftermarket brake kit, like the 355mm Brembo 6-Piston brakes, the RCM 365mm Alcon Brake kit, or the 328mm AP Racing calipers that are a bit wider than the Brembo 4-piston calipers, this is where things get more difficult because you need a wheel that has a wide enough barrel to clear the caliper, and that wheel also has to have a spoke shape that will clear the caliper as well. Often times we see reference to needing X” wide wheels, or XXet off-set wheels to clear a caliper, but if you are using a caliper that you don’t have a reference for, there really is almost no way to tell if a caliper will clear without test-fitting the wheel.

Here are some tools you can use to try to figure out wheel fitment if you are looking for bigger wheels and brakes. First, most brake manufacturers will have a fitment template that you can put into a wheel to see if you have enough clearance. If you do print one of these out, you need to make sure that the scale is 1 to 1 otherwise you won’t get an accurate assessment. You also will want to make sure that there is at least 3mm clearance to the spoke at all points to the caliper as they will flex a bit under hard cornering, etc.

The other thing that you can do is to look for a wheel that is specifically designed for large caliper clearance. This is becoming more common as more and more people are upgrading their brakes, and it is more common on Forged wheels it seems. What this means is that the wheel manufacturer is aware of the need for a lot of room under the spokes of the wheel to make room for a caliper. Generally these wheels go our from the hub quickly and return to the barrel with a sharp angle to give as much room under the spoke as possible for clearance.

One such wheel that we like a lot is the Enkei RC-T5. This is a wheel that is designed for motorsport use, and because of that, it has lots of room for big calipers.

With all that being said, if you are going with a larger brake and wheel, always test fit the wheel first before you mount tires, etc. Even if all of the calculations and templates say that your wheel should clear, double check that with an actual test before you go past the point of no returns.  The perfect example of this are the Forester Sport wheels that are on the 03 WRX Project car.  We knew that we wanted to test out the AP Racing 328mm Brake kit, but we test fit the wheels on the Stoptech kit that was on the PPIHC car.  With those calipers, the wheels would clear with a 5mm spacer, but when we put the actual AP calipers on, the wheels were just hitting the calipers.  We ended up having to go up to an 8mm wheel spacer to get them to clear the AP Racing calipers.

Hope that helps, and thanks for reading!

- Jon Cooley