What have you done to your car today?

naefeart said:
Car was into the dealer was for an oil change. While there they gave it a general inspection and top up fluids etc. They checked the tyre tread depths and in conversation tell me they recommend replacement at 3mm. This surprised me somewhat.

Of course you can view this as simple cash generation, but I thought it was a strange stance in the current environment re efficiencies and reducing pollution etc. So it got me wondering if you guys generally run your tyres all the way down to the legal limit before changing, or is there a point before this where you feel it’s preferred to change?

My tyres are 7mm and don’t need changing btw.
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For me, I gauge it. Michelin recommend that you run the tyres down to the legal limit and to change them prior to this is economically and environmentally wasteful. They say that a tyre that is approaching the end of it's life has gives a 20% decrease in rolling resistance, an increase in dry grip and wet grip which still is better than a lot of brand new tyres (probably mostly ditchfinders). Michelin are so confident of this that they are asking for tyres to be tested not only at new, but when they've worn down - I imagine it'll show that Michelins/premium tyres keep their wet grip performance a lot longer than cheap tyres (which are poor even when new) and that the cheap tyres will fall to a new level of dangerously crap wet grip as they wear.

That said, the other tyre manufacturers have said that they recommend changing them at 3mm - but you could draw the conclusion that they're only saying this to keep sales going? For me, it's just annoying. How hard would it be for an independent body to carry out all sorts of said tests on tyres? It just comes back to an absolute lack of any sort of regulation of the tyre industry and a failure to recognise the importance of good quality tyres. We've got regulation in *every* other part of our life to ensure things meet minimal standards and be classed as safe. For tyres - they basically need to have more than 1.6mm tread and nothing else.

We've now got to the stage where we've got YouTubers who have conducted more scientific and interesting tests than a lot of government bodies. It would take a government agency such a small amount of effort to conduct a scientific experiment and to publish the results.

Over the last few years, the way it's fallen for me is that as I've been coming into the summer months, my tyres are on ~3mm or so, so I've kept them on and they are normally getting to the legal depth by October sort of time when I change them.
 
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In fact, I've just found a video which answers your question pretty well.

For those who don't have time, they used a Michelin Primacy 4 brand new and one which was worn to 1.6mm and compared it to a brand new budget tyre and a budge tyre which was worn to 1.6mm.

They did several tests including dry braking, wet braking and curved aqua planing.

Dry braking - the completely worn Michelin won, followed by the new Michelin. They didn't test the budget one but from seeing lots of tyre tests, the budget would have lost
Wet braking - the new Michelin won, followed by the worn Michelin, followed by the brand new budget, followed by the worn budget
Curved aqua planing - the worn Michelins were pitched against the brand new budgets and won quite easily.

Although they didn't do all tests with all tyres, I think it's fairly easy to work out what would be the missing results and form some sort of conclusion:

- A brand new premium tyre will perform moderately better than a completely worn premium tyre in very wet conditions
- A completely worn premium tyre will perform better than a brand new budget and much better than a worn budget in very wet conditions
- A brand new premium tyre will perform less well than a completely worn premium tyre in dry braking and science tells us that it will give 20% more rolling resistance than a new tyre, less steering feel and more road noise.
- Both a brand new and completely worn premium tyre still easily outperforms anything in the budget category, new or worn

Unsurprisingly, this means a simple rule of "change at 3mm" is only partially correct, albeit very oversimplified and the science is a bit more complicated.

The more complicated version is that the tyres within their *respective category* will perform better in the wet with more tread depth. However this is only applicable when comparing within their own category. This does NOT mean you should change your 3mm Michelins/Premium tyres for some brand new Nankangs/Linglongs/Triangles/Landsails/Wanli/Rotalla/Minervas etc etc because this is likely to give significantly worse performance. However if you value wet weather performance above all else, you should consider changing your 3mm Michelins with a new set of Michelin/premium tyres.

The other thing to remember, is that these wet tests were done with a VERY wet road surface, the type you only experienced when you're going through one of those deluges and everyone (except Audis) slows down to 40-50 mph on the motorway. These happen very infrequently and it's much more likely you will be driving on a wet road rather than an absolutely soaked road in which case the difference in the tread depths will be less significant.
 
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naefeart said:
Car was into the dealer was for an oil change. While there they gave it a general inspection and top up fluids etc. They checked the tyre tread depths and in conversation tell me they recommend replacement at 3mm. This surprised me somewhat.

Of course you can view this as simple cash generation, but I thought it was a strange stance in the current environment re efficiencies and reducing pollution etc. So it got me wondering if you guys generally run your tyres all the way down to the legal limit before changing, or is there a point before this where you feel it’s preferred to change?

My tyres are 7mm and don’t need changing btw.
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I coached my mum on this the other day. She took her 4 year old Fiesta in for MOT and I knew they'd advise tyre replacement despite there being 3mm and only 12,000 miles on the car.

It does seem wasteful however her argument, albeit tenuous, was that it'll be a pain to book another garage visit in outside of service and MOT windows (already misaligned due to COVID).

It's the same as people replacing home boilers when they still work, really. It'll save a bit of $ but overall more environmentelly impacting.

I guess a 1.5mm margin for error is a lot less impactful than the entire car industry and propensity for people to constantly demand new cars which are progressively getting harder and harder to recycle with all of the complex composites and multi material components.
 
I've just watched a few other videos on the 1.6 vs 3mm question and unsurprisingly they are done by National Tyres/Autoexpress and sponsored by Continental and contain no real science. This is unfortunately what happens when it is left in the hands of people who want to sell you things to do these tests - they can easily skew them to suit their agenda. They show a Continental Premium Contact 5 at 3mm vs a 1.6mm tyre, but they tactically never show what the 1.6mm tyre is, and just refer to it as "a tyre at 1.6mm" which to me says they are carefully omitting details and they aren't comparing a 3mm Conti with a 1.6mm Conti of the same model. Without these details, the test is useless and all this serves to do is give people who only look surface deep (which most people do) a misunderstanding of the question and low and behold, will cause people to buy tyres prematurely.

The original video I posted by PetrolPed is the only one which has some decent science in, backed up by him zooming in on the tyre and tread depths of each tyre to verify that they are comparing apples with apples.
 
Gaygle said:
They show a Continental Premium Contact 5 at 3mm vs a 1.6mm tyre, but they tactically never show what the 1.6mm tyre is, and just refer to it as "a tyre at 1.6mm" which to me says they are carefully omitting details and they aren't comparing a 3mm Conti with a 1.6mm Conti of the same model
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Its like winter tyre testing all over again.

Look how much better the Super Ultra Mega Sport Ultra Performance Winter Mega Super is when it's 6c compared to 'Generic Summer Tyre!'
 
Gaygle said:

In fact, I've just found a video which answers your question pretty well.

For those who don't have time, they used a Michelin Primacy 4 brand new and one which was worn to 1.6mm and compared it to a brand new budget tyre and a budge tyre which was worn to 1.6mm.

They did several tests including dry braking, wet braking and curved aqua planing.

Dry braking - the completely worn Michelin won, followed by the new Michelin. They didn't test the budget one but from seeing lots of tyre tests, the budget would have lost
Wet braking - the new Michelin won, followed by the worn Michelin, followed by the brand new budget, followed by the worn budget
Curved aqua planing - the worn Michelins were pitched against the brand new budgets and won quite easily.

Although they didn't do all tests with all tyres, I think it's fairly easy to work out what would be the missing results and form some sort of conclusion:

- A brand new premium tyre will perform moderately better than a completely worn premium tyre in very wet conditions
- A completely worn premium tyre will perform better than a brand new budget and much better than a worn budget in very wet conditions
- A brand new premium tyre will perform less well than a completely worn premium tyre in dry braking and science tells us that it will give 20% more rolling resistance than a new tyre, less steering feel and more road noise.
- Both a brand new and completely worn premium tyre still easily outperforms anything in the budget category, new or worn

Unsurprisingly, this means a simple rule of "change at 3mm" is only partially correct, albeit very oversimplified and the science is a bit more complicated.

The more complicated version is that the tyres within their *respective category* will perform better in the wet with more tread depth. However this is only applicable when comparing within their own category. This does NOT mean you should change your 3mm Michelins/Premium tyres for some brand new Nankangs/Linglongs/Triangles/Landsails/Wanli/Rotalla/Minervas etc etc because this is likely to give significantly worse performance. However if you value wet weather performance above all else, you should consider changing your 3mm Michelins with a new set of Michelin/premium tyres.

The other thing to remember, is that these wet tests were done with a VERY wet road surface, the type you only experienced when you're going through one of those deluges and everyone (except Audis) slows down to 40-50 mph on the motorway. These happen very infrequently and it's much more likely you will be driving on a wet road rather than an absolutely soaked road in which case the difference in the tread depths will be less significant.
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Excellent, that puts it all into perspective. Guess the dealers and their ‘recommendation’ are simply playing on people’s insecurities around perceived ‘safety’.
 
Busy car day.

911 got a single stage correction - pics to follow shortly!

M4 was at the local dealership for the new M3 / M4 launch day as part of their online event, so I took a quick video while there.

 
I made it bloo

30kZyYX.jpg
 
Cleaned inside and out today but I then had an incident with a kerb... minor kerb rash but quite a lot of it so debating between a refurb or new alloy dependant on the price difference. :mad:
 
Replaced a bunch of coolant hoses today, the end of one had been perishing for a while but found loads of cracks when I checked them over. Hoping to avoid any more scenes like this :D

sLAcker.jpg
 
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