A 6x135-to-8x170 wheel adapter mounts to a vehicle with a 6x135 hub and provides an 8x170 mounting pattern for the wheel. Before buying, confirm that the adapter’s vehicle side and wheel side are specified in that direction, then verify the center bores, thickness, offset, studs, and physical clearances. Matching the bolt patterns alone is not enough to establish fitment.
Confirm the conversion direction
PCD means pitch circle diameter: the diameter of the circle through the centers of the lug holes. In 6x135, the vehicle has six mounting positions on a 135 mm circle. In 8x170, the wheel has eight mounting positions on a 170 mm circle.
Check the adapter listing or drawing for both interfaces:
| Interface | Required pattern |
|---|---|
| Adapter mounts to vehicle hub | 6x135 |
| Wheel mounts to adapter | 8x170 |
Do not rely on a listing that only says “6x135 to 8x170” without making clear which pattern is on each face. Confirm the conversion direction with the seller or manufacturer if the description is ambiguous. Also identify the exact vehicle and wheel application; a matching PCD does not confirm that an adapter clears the brakes or fits the hub.
Match the vehicle-side mounting interface
The adapter’s vehicle side must fit the hub face and its original studs. Confirm:
- The 6x135 PCD is correct for the vehicle.
- The vehicle’s stud thread matches the adapter’s vehicle-side fastening hardware.
- The hub pilot diameter and shape fit the adapter’s center bore.
- The adapter’s mounting face sits flush against the hub.
A clean, flat mating surface matters. Rust, debris, or interference around the hub can prevent the adapter from seating correctly. Check the hub-pilot length as well: it must not stop the adapter from sitting flush, and the adapter must be designed to locate properly on the vehicle hub where applicable.
Match the wheel-side pattern and center bore
The adapter’s outer mounting pattern must be 8x170, and the wheel must have that same PCD. Also compare the wheel’s center-bore diameter with the adapter’s wheel-side pilot.
There are two center-bore interfaces to check:
- Vehicle hub to adapter: the adapter’s inner bore must clear and fit the vehicle’s hub pilot.
- Adapter to wheel: the adapter’s outer pilot, if present, must fit the wheel’s center bore.
Do not assume that a wheel will be properly centered just because its lug nuts can be tightened. Determine whether the adapter and wheel use a hub-centric fit, a lug-centric fit, or a specified combination, and follow the adapter manufacturer’s design. A bore that is too small can prevent installation; excessive clearance may leave the assembly dependent on lug centering where the design does not call for it.
Choose thickness and recalculate effective offset
Adapter thickness moves the wheel outward. This changes the wheel’s effective offset and can affect fender clearance, suspension clearance, steering, and bearing loads.
For standard positive-offset notation:
Effective offset = wheel offset − adapter thickness
For example, a wheel with +20 mm offset used with a 25 mm adapter has a nominal effective offset of −5 mm. This calculation is a screening tool, not proof of fit: wheel width, tire size, suspension geometry, and the vehicle’s available clearance also matter. The adapter increases track width by its thickness on each side where installed.
Choose thickness only after checking the wheel and tire position relative to the vehicle. A thicker adapter may create more outward clearance from suspension parts, but it also moves the tire closer to the fender. Check the manufacturer’s dimensional drawing rather than estimating from a product photo.
Verify studs, threads, and outer clearance
An adapter uses fastening hardware on both sides. Match the vehicle-side hardware to the vehicle’s studs and the wheel-side hardware to the wheel’s requirements. Confirm thread diameter and pitch, nut seat type, and the specified nut style; conical, spherical, and flat seats are not interchangeable unless the wheel or hardware manufacturer specifies otherwise.
Check that:
- Vehicle-side nuts have adequate thread engagement and seat correctly.
- Wheel-side studs and nuts match the wheel’s thread and seat.
- The wheel’s lug holes and pockets clear the adapter studs and nuts.
- Original vehicle studs do not protrude into the wheel or prevent it from seating.
- The adapter clears the brake rotor, caliper, and other nearby components.
Finally, assess the complete wheel-and-tire assembly, not just the bare wheel. Confirm clearance to suspension and steering parts and to the fender through the relevant steering and suspension movement. A static visual check may not reveal rubbing at full steering lock or under compression.
Buying checklist
Before ordering, have the following confirmed against the adapter’s application data or drawing:
- Vehicle-side pattern: 6x135
- Wheel-side pattern: 8x170
- Vehicle hub-pilot and adapter inner-bore fit
- Adapter outer pilot and wheel center-bore fit
- Adapter thickness and resulting effective offset
- Vehicle-side and wheel-side stud threads, nuts, and seat types
- Stud length, thread engagement, and wheel-pocket clearance
- Brake, suspension, steering, and fender clearance
- Adapter application and load suitability for the intended vehicle and use
Use the specified installation procedure and torque values for the adapter and wheel hardware, and follow any re-torque instructions from the manufacturer. If any dimension or interface is uncertain, confirm it before purchase rather than treating the matching PCDs as a complete fitment check.
