Is it acceptable for a car's front wheels to be one size larger than the rear wheels?
2 Answers
It is not acceptable for a car's front wheels to be one size larger than the rear wheels. Here are the relevant explanations: Reasons why front wheels cannot be one size larger than rear wheels: Uneven friction distribution between front and rear wheels will lead to increased fuel consumption. The vehicle will fail relevant annual inspections. Automotive wheel regulations: The total lateral runout and radial runout of wheel assemblies should not exceed 5mm for vehicles with total mass ≤3500kg. The length of tread wear or sidewall damage must not exceed 25mm in length or depth, as this may cause abnormal wear and deformation. Special school buses must use tubeless radial tires; highway coaches, tour buses and school buses must use retreaded tires for all wheels and undergo regular inspections.
As a seasoned mechanic with several years of experience in the automotive industry, I find this issue quite tricky. From my experience, having tires with a one-size difference between front and rear is usually not a good idea. It can lead to poor handling, such as oversteering or unbalanced braking, increasing the risk of skidding. I've seen many car owners opt for larger front wheels to save money or for aesthetic reasons, only to end up with malfunctioning wheel speed sensors, ABS and ESP failures, making it especially dangerous in rainy conditions. Tire wear also becomes uneven, with wear differences of up to double being common. I recommend checking the user manual first—some vehicles support asymmetric designs, but regular family cars should never attempt this. It's best to visit a professional shop to inspect the suspension and balance, otherwise, the money saved will all go into repair costs. In short, safety comes first, unless it's a performance car modified for track use.
