Wheel Offset and Fitment: What Vancouver Drivers Should Know

Wheel fitment is one of those topics that can make a car look dramatically better or leave you dealing with premature tyre wear, rubbing issues, and a rougher ride — often without the buyer understanding why. The key number behind fitment is offset, and understanding what it actually means before you buy can save you a lot of后悔.

What offset actually measures

Offset is the distance between the wheel's mounting hub centreline and the wheel's centre plane, measured in millimetres. It is printed on the back of almost every wheel as an ET number — ET standing for Einpresstiefe, the German term for insertion depth. A wheel with ET 35 sits 35 millimetres toward the outside of the car from the hub centreline. A wheel with ET 20 sits further outward. A wheel with ET 45 sits deeper toward the engine bay.

That single number has a direct effect on how the wheel sits in the wheel well. A lower offset pushes the wheel outward — more aggressive stance, more fill in the wheel arch, and slightly wider track — but it also moves the suspension load further from the bearing centreline, increasing stress on wheel bearings. A higher offset moves the wheel inward, which can cause the tyre to rub against inner suspension components at full lock or under load.

How offset change affects suspension geometry

When you change offset, you are changing the scrub radius — the distance between the tyre contact patch and the steering axis line where it meets the ground. This is not just a measurement issue. A larger scrub radius makes the steering feel heavier and more direct, but it also increases the forces transmitted back through the steering column over bumps and through potholes. In Vancouver, where road surfaces are routinely compromised by frost cycles and heavy truck traffic, a significantly altered scrub radius can make the car feel harsh and unpredictable on the roads you drive every day.

Smaller offset changes — within five to ten millimetres of the original — generally do not produce noticeable geometry changes. Larger reductions, especially on vehicles with already-aggressive original offset, can produce steering that feels vague at the limit and increased stress on ball joints and tie rod ends over time.

Fender rolling and whether it is part of the process

When offset is lowered enough that the tyre starts to contact the inner edge of the fender lip at full suspension travel, fender rolling becomes part of the conversation. Fender rolling uses a heated roller to reshape the fender lip inward, gaining a small amount of clearance. It is a legitimate modification when done properly by an experienced shop, and it opens up fitment options that would otherwise rub.

It is not always necessary, and it is not always done cleanly on the first attempt. A poorly executed fender roll can crack the paint at the rolled edge, creating a rust starting point in a coastal city like Vancouver. The JRS team has seen both outcomes and will be straightforward about whether a roll is needed for your specific fitment choice.

The role of wheel spacers

Wheel spacers are occasionally used to push wheels outward when a desired offset is not available in the wheel size you want. The spacer sits between the hub and the wheel, moving the wheel outward by its thickness. Done properly with hub-centric installation and properly torqued hardware, spacers are a safe and reversible option. Done with poor-quality bolt-on spacers and vibration, they are a genuine safety issue.

The critical thing with spacers is hardware quality and fitment. The bolts or studs that secure the spacer to the hub and the wheel to the spacer must be the correct length and thread engagement — insufficient thread engagement is the most common failure mode with spacer installations.

Talk to JRS before you buy your next set of wheels

JRS Auto Customs works with wheel fitment daily, including projects like Audi and Porsche builds where precise offset and suspension geometry are part of the spec from the start. The team can review your proposed wheel choice against your vehicle's current setup and tell you whether the fitment will work without geometry issues, rubbing, or premature wear.