World One Performance Blog

Continuing off from yesterday’s wheel offsets discussion, since the vast majority of our clients are Subaru Impreza owners, it only made sense to discuss wheel sizes and options that fit on the Impreza, and the potential problems that might arise. As mentioned yesterday, heels have to clear 3 main things in order for them not only to fit on the car, but also roll freely: fenders, suspension, and brakes. To add complexity to this, the wheel diameter, width, offset, and even spoke design come into play. For example, even though a wheel might have a diameter, width, and offset that works fine, another wheel with the same exact measurements but a different spoke design might not clear the brakes. And of course, this depends on the brakes being used, whether it’s the stock STI Brembos, a StopTech BBK, or the 06-07 WRX calipers. The good thing though, is that we’ve installed a number of different wheel and tire setups here at our shop, so we can speak with confidence on the combinations I’m about to mention. I’ll also include the necessary suspension and/or fender modifications required for these wheels to fit without any rubbing.

For 02-09 WRX and 04 STI

The WRX and 04 STI are plagued by the 5×100 bolt pattern. This pattern is the actual distance that the lugs are spread apart on the wheel hub. While you wouldn’t think that a 14.3mm difference between the WRX and STI is a big deal, as it turns out, the wider the wheel and the lower the offset you go, the more stress you put on the wheel bearings in this bolt pattern. For this reason, many of the wheel manufacturers that we carry do not even make certain wheel fitments for 5×100. Here are a few examples that we have personal experience with:

• Volk TE37 17×8 +44 5×100 (clears STI Brembos)
• Volk TE37 18×7.5 +48 5×100 (does NOT clear STI Brembos)
• Volk CE28N 17×7.5 +50 5×100 (does NOT clear STI Brembos)
• Volk CE28N 17×9 +43 5×100 (clears STI Brembos, may require fender rolling depending on tire)
• Volk CE28N 18×8.5 +44 5×100 (clears STI Brembos)
• Volk GT-V 18×8 +46 5×100 (clears STI Brembos)
• Volk GT-S 18×8 +43 5×100 (clears STI Brembos)
• Gram Lights 57 Maximum 18×8.5 +45 5×100 (clears STI Brembos)
• Gram Lights 57 Optimise 18×8.5 +43 5×100 (clears STI Brembos)
• 57Motorsport G07WT 17×9 +45 5×100 (clears STI Brembos)
• Advan TC-II 18×7.5 +48 5×100 (does NOT clear STI Brembos)
• Advan T6 18×8 +45 5×100 (clears STI Brembos)
• Advan RS 18×8.5 +48 5×100 (clears STI Brembos)
• Advan RC-II 18×7.5 +48 5×100 (does NOT clear STI Brembos)
• Prodrive PWRC1 18×7.5 +46 5×100 (clears STI Brembos)
• Prodrive GT1 18×7.5 +53 5×100 (does NOT clear STI Brembos)
• Enkei RPF1 17×8 +45 5×100 (clears STI Brembos)
• Work Emotion CR Kai 18×7.5 +42 5×100 (clears STI Brembos)
• Work Emotion XD9 18×8 +45 5×100

As far as tire sizes go, you are of course limited to the width of the wheels that are even available to 5×100. In most cases, you can run a 245/35/18 tire no problem without any rubbing issues, but you can also run a 245/40/18 if your car isn’t lowered very much. However, a 255 tire will definitely require fender rolling and/or cutting.

For 05-09 STI

The change to the 5×114.3 bolt pattern opened up a plethora of wheel options to STI owners. Since 5×114.3 is a more universally-available bolt pattern, just about every wheel manufacturer had varying sizes of wheels that would fit. 8 and 8.5 wide fitments were almost always safe without any risk of rubbing, so long as you didn’t roll with a 245 or larger tire size. A 235 tire size is almost a sure-fire perfect fit with no rubbing issues. However, with more wheels available in 9 and 9.5 inch widths, the trend moved toward these wheel and tire sizes, which almost always require fender modification. Specifically for 9.5 inch widths, coilovers were required for suspension clearance along with rear camber bolts in order for the wheels not to rub on the fenders, which of course needed to be rolled anyway. Again, a few examples, each of course clears STI Brembos:

• Volk CE28N 18×8.5 +52 5×114.3
• Volk RE30 18×8.5 +52 5×114.3
• Volk RE30 18×9 +50 5×114.3
• Volk TE37 18×8.5 +50 5×114.3
• Volk CE28N 18×9.5 +40 5×114.3 (requires fender rolling, coilovers, and rear camber bolts for 05-07 STI only)
• Gram Lights 57 Maximum 18×8.5 +45 5×114.3
• Gram Lights 57 Optimise 18×8.5 +43 5×114.3
• Gram Lights 57F 18×8.5 +45 5×114.3
• Advan RG-II 18×8 +45 5×114.3
• Advan RS 18×9 +45 5×114.3
• Advan RZ 18×9 +45 5×114.3
• Prodrive GT1 18×8.5 +53 5×114.3
• Prodrive GC05F 18×8.5 +44 5×114.3
• Prodrive GC010G 18×8.5 +46 5×114.3
• Prodrive GC05F +44 5×114.3 (requires fender rolling, coilovers, and rear camber bolts for 05-07 STI only)
• Prodrive GC010G 18×9.5 +44 5×114.3 (requires fender rolling, coilovers, and rear camber bolts for 05-07 STI only)
• Prodrive GC010E 18×9.5 +44 5×114.3 (requires fender rolling, coilovers, and rear camber bolts for 05-07 STI only)
• Prodrive GC06H 18×9.5 +44 5×114.3 (requires fender rolling, coilovers, and rear camber bolts for 05-07 STI only)
• Enkei NTO3+M 18×9.5 +40 5×114.3 (requires fender rolling, coilovers, and rear camber bolts for 05-07 STI only)\
• Work Emotion XD9 18×9 +43 5×114.3
• Work Emotion CR Kai 18×8.5 +43 5×114.3

Obviously, with wider wheels, you can run wider tires. As mentioned above, just about everything 255 and up will require fender rolling, but we’ve managed to fit 265/35/18 and 275/35/18 after fender and suspension modification as mentioned above. The Element Tuning Time Attack Race Car pictured above runs on Prodrive GC05Fs in 18×9.5 +44 5×114.3 and 275/35/18 Hankook race slicks.

For 08-09 STI

The wider track and fenders of the 08-09 STI definitely allow for even wider wheels and tires, with much less risk of rubbing. This is partially due to the fact that the 08-09 STI comes with 18×8.5 wheels straight from the factory. All of the above wheels fit perfectly fine on the 08-09 STI, however 265 and wider tire sizes may require fender rolling, depending on how low of an offset you decide to run. Generally speaking, staying with a 05-07 STI safe offset will not require any fender modification on the 08-09 STI, and any of the 18×8.5 wheel sizes can simply reuse the stock Dunlop 245/40/18 tires. Fitment examples:

• Volk CE28N 18×9 +35 5×114.3
• Volk RE30 18×9 +35 5×114.3
• Volk TE37 18×9.5 +40 5×114.3
• Volk TE37 19×9.5 +43 5×114.3
• Advan RS 18×9 +35 5×114.3
• Advan RZ 18×9 +35 5×114.3
• Work Emotion XD9 18×9 +38 5×114.3
• Work Emotion CR Kai 18×8.5 +37 5×114.3

Again, I should stress that these are all just examples that we’ve tried here at our shop, and there are very many other wheels and sizes that will fit just fine. Just remember to do your research and if all else fails, contact us and we’ll be happy to make a recommendation!

While the first thing most people do to their car is upgrade the power, often times when it comes to wheels, many people seem to be at a loss. Often people don’t know what wheels fit their car, let alone what’s a good quality brand. However, before we get into wheel manufacturing technology (which we’ll go over in a future blog entry), let’s start with the basic wheel feature that affects how wheels will both fit and look on a car: wheel offset.

Whenever your look up wheel specs, they usually have a listing of offsets, such as +53, +45, +29, and so on. These offsets represent the distance in millimeters that the wheel hub (where you actually mount the wheels onto the car) is from the centerline of the wheel. I created this diagram from a Volk TE37 for Porsche wheel to help illustrate:

As you can see, I’ve placed a line the goes down the center of the wheel, and I’ve shown that the right side of the wheel is on the outside toward the fender, whereas the left side of the wheel is on the inside toward the suspension. As the diagram shows, the wheel hub is directly on the center line, which means it has a zero offset. When the wheel hub is pushed out toward the outside of the wheel, then the wheel has positive offset; when the hub is pushed in toward the inside of the wheel, then the wheel has negative offset. Makes sense, right? Perhaps it does, but how does this affect wheel fitment?

Herein lies the problem with offset. Wheels have to clear 3 main things in order for them not only to fit on the car, but also roll freely: fenders, suspension, and brakes. Since ever car is different, not every wheel offset will work. Some cars, such as the 350Z and M3, have plenty of room between the outside fender and the suspension. Other cars, such as the 93-01 Impreza, have nowhere near as much space. Still other cars, such as the S2000 have an average amount of room in the front of the car, but barely any room in the rear. On top of all this, wheel offsets are also affected by the width of the wheel. Thus, a wheel that is only 7.5 inches wide fits differently than a wheel that is 10.5 inches wide with the same exact offset. Remember, the offset is measured from the centerline of the wheel, so the wider the wheel, the distance available from the centerline. This can very much come into play when there’s a big brake kit on the car, since you’ll need to choose an offset that will clear the brake calipers.

Despite all the possible complications, here are a few generalizations that will help with your wheel offset decisions:

• High offsets (such as +50 for example) make the wheel fit inward toward the suspension. This helps the wheel clear the outside fender, but since the wheel goes in more, it could pose problems clearing brakes or contacting the suspension.
• Low offsets (such as +25 or anything in the negative for example) make the wheel fit outward toward the fender. This helps the wheel clear a big brake kit, but it could pose problems with your wheels and tires rubbing against your fenders.
• Since every car is different, certain offsets (typically lower offsets) combined with a certain wheel bolt pattern can cause undo stress on your wheel bearings, causing them to wear out prematurely. For this reason, many wheel manufacturers simply do not manufacture wheels in certain fitments.

So how do you decide what’s the best wheel offset for your car? First off, do your research: find out what your stock wheel offset is first and foremost, and then you can even measure yourself to determine how different of an offset will suit your needs. Also find out what other people with your same car are running and find out if they have any wheel fitment problems. After you’ve done your research and you’re still unsure, please don’t hesitate to contact us, since we are familiar with a great many different wheel options and fitments for various vehicles. If you find out that the size and offset you need aren’t readily available, we can always special order you a set and, depending on the brand, even custom order a set of wheels to your exact specifications. Coming up tomorrow, we will share some typical wheel and tire fitments that we’ve tested out at our shop and what modifications were necessary to make them fit without any fender rubbing or suspension contact.