Where I live, summer tires are required by law to have 1.6 mm minimum tread depth, and winter tires 3 mm. However, a general recommendation is that summer tires should have 4 mm tread for optimal resistance against hydroplaning.

However, there are various sizes of tires and cars. Tires can be smaller or larger in radius, or narrower or wider in width. Similarly, vehicle weight varies a lot, and a small hatchback can weigh half of that of a big electric SUV.

My SUV for example had 8.3 mm initial tread depth on the stock summer tires, far more than my previous small hatchback had. But the tires are both larger in radius and width, and the vehicle weight is nearly 50% more than in the previous small hatchback.

Is there any information on whether tire size (radius or width), or vehicle weight affect the safe minimum tread depth needed to avoid dangerous hydroplaning?

1 Answer 1


Hydroplaning will occur in any tire no matter size or width whether having specifically designed rain tires (ever watch F1 racing in rain?), street vehicles with or without rain tires in regions expected to rain often, regular all season tires, using them as new, worn or near minimum tread depth. It doesn't matter whether it's the new 5k lb BMW ev SUV with 22" tires, average car, suv or smallest car with narrow tires. All will hydroplane when unfamiliar with tire traction in wet, slick conditions in rain, snow or ice. To appreciate loss of tire traction, practice on sandy, gravel roads free of traffic or wet parking lots away from parked vehicles. Accelerate straight to 25-45 mph then brake hard, expecting abs to kick in with the foot massage. Allow plenty of stopping distance and a wide area in these tests. You can learn a lot from your vehicle and yourself in wet conditions in a relatively safe test setting instead of finding out the hard way in poor weather. Understanding your personal driving limits, your vehicle handling in wet conditions no matter what tires are used can help you drive safer (from testing) in almost any poor weather.

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