Technical Articles

Quick Guide to Upsizing Custom Wheels

Touren custom wheels TR91 3291 black on Infiniti

It doesn’t matter if you drive a new 4×4, a classic muscle car, a daily driver, or a high-performance vehicle; you should think about upsizing your wheels. Upgrading your vehicle by moving to upsized custom wheels not only improves your ride’s appearance and performance, but it also offers several other benefits. Larger custom wheels will fill those wheel wells better, enhancing the overall aesthetics. Moreover, upsized custom wheels can significantly improve the performance of your ride. When it comes to aftermarket modifications, upsizing to custom wheels provides incredible bang for the buck. Now, let’s delve into what you need to know about buying upsized custom wheels.

Upsizing Custom Wheels Enhances Performance

As the size of your custom wheels goes up, the standing size of your tire must go down. We’ll get into why in just a bit. For now, trust me on this. That lower tire standing size is the source of enhanced performance. Tires with a lower standing size get a better grip on the road. Also, as the tire gets wider you get a larger surface area for more grip. When it comes to performance, it pays to pay attention to the surface area under the tire.

C8 Chevrolet Corvette with Rotiform KPS Wheels

Car and Driver performed their own tests to see if upsizing to custom wheels really did make a difference. They discovered that wider wheels and tires exhibited better grip, braking, and even a more comfortable ride. Off-road drivers get less sway and way more stability. The only downside they uncovered is that bigger wheels often weigh more. And as unsprung weight goes up, fuel efficiency goes down. But with so many hybrids and electrics on the road today, that downside is getting smaller and smaller. Truly a small price to pay for such a vast improvement in looks and performance.

How to Calculate Wheel and Tire Size for Upsizing

Cars, trucks, and SUVs are the result of thousands of hours of careful engineering. Before the first prototype is made, engineers are already thinking about how the drive train and the wheels and tires will work together. Once in production, your ride was engineered to run on a fixed overall wheel and tire outside diameter. This overall diameter is the basis used to calculate the distance the wheel and tire travel with a single revolution. That’s an important bit of information and it determines the correct calibration of the:

  • speedometer
  • odometer
  • transmission shift points
  • traction control
  • torque

The distance traveled with a single revolution is so important that when you change the size of the wheel you must maintain the total diameter of the wheel and tire. Wheels are measured in diameter and width. So, the Advanti Racing 80B Hybris wheel that’s 18×8 has a diameter of 18” and a width of 8”.

Remember, as you increase or upsize the custom wheel size you must decrease the standing height of the tire by the exact same amount. This way you will always maintain the same overall total wheel and tire diameter. For example, if you go up an inch in wheel diameter, you must go down an inch in the standing height of the tire. Every inch you gain in wheel diameter you lose in tire standing height.

Too Much of a Good Thing

Upsizing your custom wheels unlocks the door to some great looks for your ride. But remember good things should be enjoyed in moderation. I’ve seen streets littered with cars that were upsized with abandon and wanna-be donks. Don’t be that person.

upsizing gone wrong charger on 36 inch rims

This poor Charger is all rim and no tire. The paint job is a work of art, but upsizing custom wheels to the extreme just ruins the entire vehicle. Who told them this would look good? Control your enthusiasm when upsizing. Otherwise, you’ll end up with wheels and tires that no longer fit the wheel well or cause a host of other problems.

You want this look.

Mercedes-Benz G550 with Mazzanti - M263 Wheels

Upsizing with these Niche M263 Mazzanti Wheels nicely improves this Mercedes.

In addition to keeping the overall diameter the same when you upsize, keep these factors in mind too:

Custom Wheels Offset

Offset refers to the distance of the centerline of the wheel to the mounting surface. You’ll see the offset expressed as zero, positive, or negative. Furthermore, it is essential to always pay attention to the offset. Changing too much where the wheel sits can place stress on the bearings.


Give your brakes plenty of room and be mindful of crowding the calipers. If you haven’t lifted the suspension and you haul heavy loads in your truck, the additional weight can be a problem when excessively upsizing wheels.


Custom aftermarket wheels are manufactured to fit a variety of vehicles. To accomplish this, the center bore is very large. Install your upsized wheels using hub-centric rings to reduce vibration and to protect your wheel bearings and ball joints.

Need to Double-Check Your Specs When Upsizing Custom Wheels?

If you still aren’t sure if you are upsizing custom wheels and tires properly, don’t sweat it. Just reach out to the SEMA-trained pros at WheelHero to verify your fitment.

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