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Minimum tread depth - 3/32 for NSX?

5 January 2012
Phoenix, AZ
Hi, folks,

In general, I change the tires on my cars when the guy at the shop measures them at 3/32.

Is 3/32 a reasonable minimum tread for a street-only NSX that won't ever see snow (SF Bay Area). Or are there performance/safety issues that would set a higher threshold for this car?

Thanks! -A
I believe that is the minimum legal tread depth. Any less and you can be cited for bald tires. Even at depths more than 3/32 hydroplaning can be an issue depending on speed and amount of standing water.
California Vehicle Code states this:
CA VC 27465 said:
27465. (a) No dealer or person holding a retail seller's permit shall sell, offer for sale, expose for sale, or install on a vehicle axle for use on a highway, a pneumatic tire when the tire has less than the tread depth specified in subdivision (b). This subdivision does not apply to any person who installs on a vehicle, as part of an emergency service rendered to a disabled vehicle upon a highway, a spare tire with which the disabled vehicle was equipped.
(b) No person shall use on a highway a pneumatic tire on a vehicle axle when the tire has less than the following tread depth, except when temporarily installed on a disabled vehicle as specified in subdivision (a):
(1) One thirty-second (1/32) of an inch tread depth in any two adjacent grooves at any location of the tire, except as provided in paragraphs (2) and (3).
(2) Four thirty-second (4/32) of an inch tread depth at all points in all major grooves on a tire on the steering axle of any motor vehicle specified in Section 34500, and two thirty-second (2/32) of an inch tread depth at all points in all major grooves on all other tires on the axles of these vehicles.
(3) Six thirty-second (6/32) of an inch tread depth at all points in all major grooves on snow tires used in lieu of tire traction devices in posted tire traction device control areas.
(c) The measurement of tread depth shall not be made where tie bars, humps, or fillets are located.
(d) The requirements of this section shall not apply to implements of husbandry.
(e) The department, if it determines that such action is appropriate and in keeping with reasonable safety requirements, may adopt regulations establishing more stringent tread depth requirements than those specified in this section for those vehicles defined in Sections 322 and 545, and may adopt regulations establishing tread depth requirements different from those specified in this section for those vehicles listed in Section 34500.

Section 34500 refers to Buses, Tractors, semi trucks, trailers, etc.
Therefore for a Passanger car in CA, the legal limit is One thirty-second (1/32) of an inch
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Thanks, Adrian,

This doesn't apply to implements of husbandry? Dang!

So, I'm summarizing your post to say it's a legal minimum of 1/32. (Section 34500 is for heavy vehicles like buses or trucks.) That little tread seems pretty bald to me.

The question, though, is what's the recommended minimum tread for a sports car like the NSX?
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The question, though, is what's the recommended minimum tread for a sports car like the NSX?

Watch this video and then decide. :smile:
<iframe width="560" height="315" src="http://www.youtube.com/embed/zA6MUlVNkLM" frameborder="0" allowfullscreen></iframe>

Here's the full report.. if you only drive ONLY in Dry conditions, then the minimum tread depth isn't much of an issue.
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I had to google "Implement of Husbandry." It wasn't as naughty as I thought:

V C Section 36000 Implements of Husbandry Defined

Implements of Husbandry Defined

36000. An "implement of husbandry" is a vehicle which is used exclusively in the conduct of agricultural operations.
An implement of husbandry does not include a vehicle if its existing design is primarily for the transportation of persons or property on a highway, unless specifically designated as such by some other provision of this code.

In most states, tires must have at least 2/32" of tread depth. Also, by federal law, all tires have treadwear indicator bars molded into the tire tread, that are flat across when the tread depth reaches 2/32".

As Hapa88 notes, the main concern with lower tread depth is traction in rain. Tire Rack testing has shown that, in rain, braking distances double at 2/32" compared with tires with full (new) tread depth, and that braking distances are 50 percent higher at 4/32" tread depth than with new tires. So if you plan on driving in rain, you may want to replace tires at 4/32" and/or before they reach 2/32".
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Since rain happens: What I think I'm hearing is that a safer minimum tread depth is 4/32 instead of 3/32.