California's tread depth regulations - why the discrepancy between legislation & inspection manual?

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Tony-cums@reddit

If you’re rolling around on 2/32 - get new tires.

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MichiganKarter@reddit

During the dry season in SoCal you can run all the way to the cords. Waste not, want not, just replace them before the rain comes back in October.

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Tony-cums@reddit

You sound so smart. This can affect stopping distance too. And control. Just do us all a favor and get a bus pass.

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MichiganKarter@reddit

Stopping distance is better on slicks than treaded tires.

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Tony-cums@reddit

This isn’t a slick compound you complete buffoon.

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Some-Internet-Rando@reddit

I was gonna say -- I would never drive on less than 3/32 and I typically change at 4/32 or higher. Hydroplaning is a thing I don't like.

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100%, but I'm interested to know how the inspection stations & CHP interpret the legislation & inspection procedures - what do they actually DO? For heavy vehicles, the legislation DOES actually state to measure the major grooves, so it appears that the legislation for light vehicles really does seem to mean that minor grooves should be assessed, which is HIGHLY unusual - globally, the standard is to ONLY assess the major grooves, and then inspect the other areas for genuine defects (exposed cords etc)

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ObviousAlias7@reddit

1/32" or 2/32" is splitting hairs here. You should get new tires before you even get to this point. Both of those numbers are low enough to have you lose traction in the wet.

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miwi81@reddit

…or the dry

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resonantpeak@reddit (OP)

No, not in the dry - the LESS tread, the better in the dry.

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miwi81@reddit

That is simply not true. The tread blocks are intended to flex, conform to the road surface, and provide consistent handling when cornering. *Bald tires are NOT racing slicks.* Slicks are engineered with sticky compound. Bald tires are hard and brittle.

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cpsdiablo@reddit

Just FYI, early 90s Showroom Stock cars ran on the same tires you could buy at any shop (initially Firestone IIRC), no fancy compounds allowed. Prior to sessions, their crews would shave the treads off the tires to increase the contact patch, and therefore grip levels.

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miwi81@reddit

That’s different than a tire that has been in the sun for 5+ years, is dryrotted, has been heat cycled a million times, has occasionally been run underinflated, and is hardened.

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cpsdiablo@reddit

None of your caveats are actually applicable.

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miwi81@reddit

OK 👍

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cpsdiablo@reddit

"That is simply not true. The tread blocks are intended to flex, conform to the road surface, and provide consistent handling when cornering. *Bald tires are NOT racing slicks.* Slicks are engineered with sticky compound. Bald tires are hard and brittle." That's a blanket statement, suggesting a hard rule. "That’s different than a tire that has been in the sun for 5+ years, is dryrotted, has been heat cycled a million times, has occasionally been run underinflated, and is hardened." This is a bunch of caveats that would cause the street tire to have little grip left, regardless of the tread-life. Hence, your caveats do not apply to the original statement.

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resonantpeak@reddit (OP)

"The good news for motorists is that as long as tyres are not damaged in any way, the safety on dry roads actually improves as their tyres get worn. As seen on race circuits around the world, in dry conditions the ‘slick’ is the tyre of choice; and similarly for the ordinary motorist, levels of grip in dry conditions increase as the tyre tread depth reduces. A worn tyre will stop a vehicle more quickly in the dry than the same tyre when new." https://mb.cision.com/Public/55/2276201/8e33562e02c19f06.pdf?hl=en-AU

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MysticMarbles@reddit

I mean, it's California. I'd run em right down to nothing if it wasn't my daily.

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kbfg2421@reddit

Ive lived in CA my whole life and ive never seen CHP or a smog (emissions) inspection station give one single fuck about the condition of your vehicles tires, brakes, suspension etc on light vehicles. Semi trucks? Yeah, they are hard asses. In CA all they give a fuck about when it comes to light trucks and passenger cars is that your shit passes emissions, its isnt loud, and you have current registration and insurance. But yeah, if your tires are bald, dont change them because you think that state is going to punish you for it. Change them because they need to be changed, and will ensure better safety for you and your passengers on the road.

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decadentmom@reddit

The likelihood that anyone looks at the tires on your vehicle are slim to none in California so who cares if its 1/32 or 2/32. Secondly, people keep mentioning "commercial" vehicles as if that is a big deal. Pickup trucks in California are all registered as commercial vehicles. Im not sure people realize that and are assuming they are referring to the big heavy weight trucks when indicating "commercial." All trucks are commercial vehicles if you live in California.

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resonantpeak@reddit (OP)

Transport providers (taxis etc) have annual inspections too.

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decadentmom@reddit

The average person in California will never have anyone inspect the tires on their vehicle EVER.

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resonantpeak@reddit (OP)

Yes, but NON average people DO.

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decadentmom@reddit

If you are driving people around and getting paid to do it hopefully you have enough common sense to have more than 1/32 of tread on the vehicle period. You shouldn't need someone to police you in order for you to figure that out.

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resonantpeak@reddit (OP)

You can't answer my question, obviously, and that's fine.

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AwarenessGreat282@reddit

I'd say they measure any groove as long it is 1/32" deep but if they are Fed inspectors, they'd look for 2/32" deep. Seems sensible to me if that is what is written.

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resonantpeak@reddit (OP)

The federal standard is 2/32" in the major grooves - that makes a big difference, because the minor grooves are shallower, and it's conceivable that in some cases the major grooves would still be above 2/32" by the time the shallowest minor grooves reached 1/32", particularly because the edges typically only contain minor grooves, and often wear faster than the middle of the tread.

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AwarenessGreat282@reddit

Ok, but you said neither mentions major grooves. I looked it up: Cali requires 1/32 on any 2 adjacent grooves, 4/32 on all major grooves of steering axles and 2/32 on major grooves of other tires. 6/32 on all major grooves of snow tires.

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resonantpeak@reddit (OP)

I said neither the Californian legislation, or their inspection manual, mentions major grooves. The federal standard DOES specify major grooves only. Again - if the wording in the Californian legislation & inspection manual is taken literally, it could actually result in a stricter requirement in many situations than the federal standard, due to the fact that in California, ANY grooves can be measured - not just the major ones.

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AwarenessGreat282@reddit

But the Cali rule does mention major grooves. Read what I commented.

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resonantpeak@reddit (OP)

It does NOT. For light vehicles, California does NOT say to only measure the major grooves.

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AwarenessGreat282@reddit

So this doesn't apply to all vehicles only commercial vehicles? [CA tire code](https://california.public.law/codes/vehicle_code_section_27465)

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resonantpeak@reddit (OP)

Yes, it applies to all vehicles, but you're misinterpreting it. Read it carefully. All the clauses that mention major grooves apply to vehicles OTHER than light vehicles.

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AwarenessGreat282@reddit

Sure, but how does it make it "stricter"?

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resonantpeak@reddit (OP)

Because the minor grooves are shallower, and also, the edges often wear more than the center, and the edges typically only have minor grooves. Some tyres actually have lateral major grooves, and in that case, I suspect an inspector would focus on the center - not the edges. If the inspection manual, which states 2/32", was taken literally, that then would be REALLY strict.

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Which_Initiative_882@reddit

The only time CHP is going to look at your tires is if they are having a REAL bad day, you did something to piss them off, or have an obvious defect like wire showing, have zero tread remaining(like a slick) or a sidewall bubble.

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tripleriser@reddit

This guy is over here trying to daily a set of Hoosiers

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gluten_heimer@reddit

California doesn’t have such an inspection.

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resonantpeak@reddit (OP)

They don't have mandated regular inspections, but there are certain situations when an inspection is performed. Also, the police may inspect the tyres.

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illegal_miles@reddit

If you aren’t driving a commercial vehicle you almost certainly are not going to be inspected in California. There are fuckers driving on bald tires with plates that have expired 2020 tags driving 15 mph over the speed limit and they aren’t getting pulled over, let alone inspected.

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Competitive-Fee6160@reddit

i replace when it gets to 2/32 always, though i’m guessing it doesn’t rain as much out there

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congteddymix@reddit

I wonder if the California law is outdated or something cause I believe that federal(which overrule state laws generally)law states that 2/32nd is the minimum tread allowed hence why the wear bars in tires are 2/32nd of an inch. The B.A.R is not a law making authority so I am sure the 1/32 you say cali has is probably technically legal. I don’t live in Cali though so I can’t state for sure. As far as inspections it’s probably a grey area, cause there could be a tire with perfectly fine tread that has about five other things wrong with it that make it not pass inspection. So take that for what it’s worth.

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SkeletorsAlt@reddit

You are unlikely to get a worthwhile answer to a legal question here. Just guessing, but have you looked at the administrative code that this “BAR” agency operates under?

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