Discovering that your new vehicle came from the factory with the wrong tire size can be frustrating—and potentially unsafe. From inaccurate speedometer readings to premature tire wear or warning lights that won’t stay off, a tire-size mismatch can create ripple effects across modern safety and performance systems. If you’re facing repeated visits to the dealership with no real fix, you may be wondering how California’s Lemon Law applies. This article explains the basics in plain language so you can better understand your options and what to document before speaking with a lawyer.
California Lemon Law: Factory Tire Size Errors
A factory tire size error can mean the vehicle was delivered with tires that don’t match the size listed on the door-jamb placard, owner’s manual, or build specifications. It can also mean a calibration mismatch—where the vehicle’s electronics (such as ABS, stability control, and speedometer) were set up for one size but different tires were installed. For example, a car listed for 235/60R18 tires might arrive with 225/55R18s, changing the rolling diameter enough to affect speed readings and braking stability.
Why does this matter? Tire diameter and load ratings are integral to how your vehicle’s systems behave. The wrong tire size can trigger TPMS or ABS alerts, cause traction control to intervene at odd times, lead to braking inconsistencies, throw off the speedometer and odometer, and even cause rubbing or steering pull. Over time, owners may see uneven tire wear, reduced fuel economy, and vibration issues that don’t fully go away with balancing or alignment because the underlying size or calibration isn’t correct.
If you suspect a factory tire-size problem, simple steps can help you build a clear record. Compare the tire size printed on your tires with the vehicle’s placard and the owner’s manual. Save photos of the placard, the tire sidewalls, and any dashboard warnings. Keep every repair order, alignment printout, and technician note, and ask the service advisor to document your concern as “tire size mismatch/factory spec discrepancy” or similar language so the paper trail reflects the issue you’re experiencing.
Do Incorrect Tire Sizes Qualify Under CA Lemon Law?
California’s Lemon Law (the Song-Beverly Consumer Warranty Act) generally applies to new vehicles—and many used vehicles still under the manufacturer’s warranty—when there’s a defect covered by warranty that substantially impairs use, value, or safety and the manufacturer (through its dealers) can’t fix it after a reasonable number of attempts. A tire-size mismatch can fall into this category when it leads to ongoing safety warnings, drivability problems, or repeated repairs without resolution. The key is whether the issue materially affects the vehicle and remains unresolved under warranty.
What counts as a “reasonable number” of repair attempts depends on the facts. The law includes helpful guidelines: for serious safety issues, fewer attempts may be considered reasonable; for other problems, more attempts may be expected; and a vehicle out of service for a cumulative 30 days can also be significant. In practice, owners dealing with repeated TPMS/ABS lights due to size/calibration errors, persistent pulling or vibration, premature tire wear caused by mismatch, or speedometer inaccuracies that the dealer can’t correct may be looking at a potential lemon scenario—especially if the dealership has had several documented opportunities to fix it.
Not every tire problem is a lemon. Road hazards, post-sale modifications, or using aftermarket tires outside specifications can complicate warranty coverage. Still, if the wrong size was installed at delivery, or the vehicle’s systems were calibrated for a different size and the dealership can’t align the hardware and software to factory spec, you may have a warranty nonconformity. Practical next steps include: avoiding modifications while the issue is evaluated; asking the dealer whether a factory Technical Service Bulletin (TSB) applies; requesting that calibration steps be performed and noted; and keeping thorough records of all visits, parts replacements, and test-drive observations.
This overview is for general informational purposes only, not legal advice, and reading it does not create an attorney–client relationship. Vehicle problems are fact-specific, and outcomes depend on the details of your situation, your warranty, repair history, and California law. If you believe your vehicle may qualify as a lemon due to a factory tire size error or related calibration issues, contact ZapLemon through our website to request a consultation and discuss your options with a professional.