How do I measure the correct spacer size for my setup?
Measuring the correct spacer size involves understanding your current wheel offset, desired stance, available fender clearance, and inner suspension clearance. Getting these measurements right before ordering ensures your spacers achieve the look and fitment you are after without causing rubbing or clearance issues.
Choosing the right spacer thickness is not a guessing game, and getting it wrong can result in tires rubbing on fenders or suspension contact that causes damage. Here is a practical guide to measuring and selecting the correct spacer size for your specific vehicle and fitment goals.
Understand What a Spacer Actually Does to Your Fitment
Before measuring, it helps to understand exactly what adding a spacer does to your wheel and tire position. A spacer pushes the entire wheel and tire assembly outward from the hub by the thickness of the spacer. A 20mm spacer moves the wheel 20mm further outward from its current position. This effectively changes the offset of the wheel by the same amount, making the effective offset 20mm lower than it was before the spacer was added.
Because the wheel moves outward, the outer edge of the tire gets closer to the fender while the inner edge moves further away from suspension components. Both of these clearance changes need to be measured and verified before committing to a spacer size.
Measure Your Current Outer Fender Clearance
The most important measurement for determining how much spacer thickness you can safely run is the gap between the outer sidewall of your tire and the inner edge of your fender or fender liner. This measurement tells you the maximum amount the wheel can be moved outward before the tire contacts the fender.
To take this measurement, park the vehicle on a level surface and turn the steering wheel to full lock in both directions to find the tightest clearance point, which is typically somewhere in the arc of the front tires during full steering lock rather than when the wheels are pointed straight ahead. Use a ruler or tape measure to measure the horizontal distance between the outer sidewall of the tire and the fender edge or fender liner at the tightest point. This measurement represents the absolute maximum spacer thickness that could be used before contact occurs, and staying below this maximum with a meaningful safety margin is strongly recommended to account for suspension compression while driving.
A general guideline is to leave at least 5mm to 10mm of clearance after the spacer is added to account for suspension movement, tire flex under load, and any slight inaccuracies in measurement. If your fender clearance is 25mm, a spacer in the 15mm to 20mm range is a safer choice than going to the full 25mm limit.
Check Your Inner Suspension Clearance
While outer fender clearance gets the most attention when sizing spacers, inner clearance is equally important. When the wheel moves outward, the inner edge of the wheel moves further away from the suspension components, which actually improves inner clearance rather than reducing it. However, if you are adding spacers to a setup that already has limited inner clearance, verifying that the spacer and wheel combination still clears all inner components including brake calipers, shock bodies, and control arms is important.
In most cases adding spacers improves inner clearance, but on setups with unusual wheel widths or particularly tight inner fitment, this is worth confirming through a careful test fit before driving.
Factor in Suspension Compression
Static measurements taken with the vehicle at rest do not tell the whole story of how clearances change while driving. When the suspension compresses over bumps or under load, the wheel moves upward relative to the fender, reducing the vertical and sometimes horizontal clearance between the tire and the fender significantly compared to what is visible at rest. This is the most common reason that a spacer size that looks fine during a parked inspection causes rubbing under real driving conditions.
For daily driver trucks used primarily on pavement, leaving at least 5mm of clearance beyond the spacer thickness as a buffer is a reasonable minimum. For trucks used off-road where suspension compression is more aggressive and unpredictable, leaving a larger buffer of 10mm or more is the more conservative and appropriate approach.
Account for Steering Angle
As mentioned in the fender clearance measurement step, the tightest clearance point for front tires is almost always during full steering lock rather than when driving straight. When measuring fender clearance to size your spacers, always check at full lock in both directions rather than just with the wheels pointed forward. A spacer size that clears comfortably when driving straight may cause contact during parking maneuvers or tight turns if the full-lock clearance was not verified.
Use the Offset and Backspacing Calculators
The website has offset and backspacing calculators available that can help you determine the effective offset change that a given spacer thickness will create for your specific wheel width and current offset. Using these calculators alongside your physical clearance measurements gives you a more complete picture of what a specific spacer size will do to your overall fitment before you commit to purchasing.
When to Consult the Fitment Team
If you are unsure about your measurements, are working with a modified suspension setup that makes standard clearance estimates less reliable, or simply want a second opinion before ordering, reaching out to the fitment specialists is always a worthwhile step. Providing your year, make, model, trim level, current lift height, wheel width, current offset, and your fender clearance measurements gives the team everything they need to help you identify the right spacer size for your specific goals.
Perform a Test Fit Before Driving
After installing spacers, performing a full test fit before driving is essential. Hand tighten the lug nuts, check clearance around the fenders at full steering lock in both directions, and inspect inner clearance as well. Lower the vehicle and verify clearance under the weight of the vehicle before torquing everything to spec and taking the vehicle out for the initial drive. Any product that shows signs of being driven on cannot be returned, so catching any clearance issues during the test fit before driving protects both your investment and your vehicle.
Have Questions About Spacer Sizing for Your Setup?
If you want help confirming the right spacer size for your vehicle and fitment goals, the customer support team is happy to assist. You can reach out through the Contact page on the website and a team member will be glad to work through the details with you.