Tyre Tread Depths

[monya]

Do new tyres, premium makes eg michelin, Continental etc, have the same tread depth, or do they vary between makes or even within them, for the same size tyre?

I could swear that these michelin primacy hp on this car of mine seem to have less depth than the michelins on my previous A class which had 15'' wheels. Which probably means I can expect fewer miles on them

My old A class had the original rear tyres from new after 74000 miles. Is this a record? and yes they were legal!

[Sagitar]

Do new tyres, premium makes eg michelin, continental etc, have the same tread depth, or do they vary between makes or even within them, for the same size tyre?

I could swear that these michelin primacy hp on this car of mine seem to have less depth than the michelins on my previous A class which had 15'' wheels. Which probably means I can expect fewer miles on them

My old A class had the original rear tyres from new after 74000 miles. Is this a record? and yes they were legal!

You don't say what tread depth you have actually got. The industry standard for a car tyre is normally around 9mm. It's a compromise between wear capability, ability to cope with surface water and tread stability. Putting on a deeper tread will allow more wear and give deeper channels to carry away water, but the tread becomes unstable and road holding suffers.

I am sure that the tread depth on the Michelins fitted to my Prius were not much over 8mm when new. I put on Continental winter tyres last winter and with them, the tread depth when new was over 9mm, but the tread structure on winter tyres is different than on the summer ones.

The wear characteristics of a tyre will depend upon its width as well as its tread depth and form. Road holding, specifically, the coefficient of friction of the tyre depends partly of the state of the elastomers in the carcass, so don't expect old tyres to compare with new ones even if they are not badly worn. For winter tyres, I believe that three years is the generally accepted effective life span, but I would expect summer tyres should go longer than that, because they start with harder elastomers.

[monya]

Congratulations You are the first chap that I know of who changes over to winter tyres which I'm sure can be very sensible if you live up north.

[Sagitar]

changes over to winter tyres . . . very sensible if you live up north.

It's very sensible if you live anywhere where the average winter temperature is lower than 7 degrees C.

[BlueValour]

What are the costs involved in using winter tyres; presumably four spare wheels are need?

[Sagitar]

What are the costs involved in using winter tyres; presumably four spare wheels are need?

There is a variety of ways of doing it, but the most common approach is four extra wheels. I think the biggest problem for most people is probably storage. I'm lucky enough to have a double garage with only one car, so not a problem for me . . . ;)

[timberwolf]

Wow, a garage that is large enough to take a car.

You forgot to mention how utterly unhelpful Toyota were when you tried to find the specification for the wheels.

[Jan&tone]

Wow, a garage that is large enough to take a car.

You forgot to mention how utterly unhelpful Toyota were when you tried to find the specification for the wheels.

A garage that is large enuf to take a car is a rarity these days!

However as to the size for winter tyros, surely they should be the same size as the originals??

[timberwolf]

Erm, the wheel as in the metal bit in the centre, wot the tyre is fitted onto. :)

[Jan&tone]

Really? Wow

[Sagitar]

You guys are hilarious . . . .

It's true that the dealer staff refused to give me details of the wheel dimensions, but the info. is actually marked on the wheels and the makers of after market wheels are very helpful. I would have been pleased to buy Toyota wheels but their prices were OTT. I bought a set of four for less than the price of a single Toyota wheel. The wheels that I bought meet European industry standards and apart from possible aerodynamic differences ought to be no less serviceable as winter wheels than the Toyota kit.

My 17 inch wheels are marked 17 7J 50 i.e. they have a 50mm offset. I have never seen a 15 inch Prius wheel but I am told that they are marked 15-6JJ-45 i.e. they have an offset of 45mm.

The wheel centre distances are not therefore the same and I think should give a slightly smaller turning circle for the 15 inch wheel.

I bought 15x6.5 wheels with offset of (I think) 40mm. I wouldn't bet my life on the 40mm figure. The wheels are on the car and the markings are not visible. I bought them a year ago and my memory isn't what it was, but the significant thing was that the outer edge of the tyre finished within a millimetre or two of the summer wheels.

So, my summer tyres are 215/45 on 17x7 wheels with 50mm offset and my winter tyres are 195/65 on 15x6.5 wheels with 40mm offset.

Because the winter tyres are 20mm narrower than the summer tyres, the offset is not critical to a mm or two.

When buying 15" wheels you do need to be sure that there is sufficient clearance for the brake parts and to be sure that the wheels are hub-centric.

[johalareewi]

Or you could just swap the tyres over and store your summer tyres in the garage. You can buy the tyres on line then find a friendly fitter to swap them over. Come summer, just swap them back. Saves on wheels but you will get 2 lots of tyre fitting fees each year instead.

[Sagitar]

Or you could just swap the tyres over and store your summer tyres in the garage. You can buy the tyres on line then find a friendly fitter to swap them over. Come summer, just swap them back. Saves on wheels but you will get 2 lots of tyre fitting fees each year instead.

Absolutely right, but I gather that a narrower tyre works a bit better on snow and I was keen not to drive on low profile tyres in the winter. If I am going to slide, gently I hope, into a kerb, then doing it on higher profile tyres is likely to do less damage.

[Sagitar]

Or you could just swap the tyres over and store your summer tyres in the garage. You can buy the tyres on line then find a friendly fitter to swap them over. Come summer, just swap them back. Saves on wheels but you will get 2 lots of tyre fitting fees each year instead.

I just found this link on another site.

[johalareewi]

That was looking good until "The alloy wheel and tyre packages are offered with either Pirelli or Continental rubber."

The temperature has warmed up again here so can put off the winter tyres for a few days.

[Jan&tone]

That was looking good until "The alloy wheel and tyre packages are offered with either Pirelli or Continental rubber."

The temperature has warmed up again here so can put off the winter tyres for a few days.

Johal - according to your notes, you live in Southampton... how come you swap your tyres over??? I'd be surprised if you actually got any snow down there, let alone enough to warrant spending out on special tyres???

- not being funny btw, just curious..

[johalareewi]

Johal - according to your notes, you live in Southampton... how come you swap your tyres over??? I'd be surprised if you actually got any snow down there, let alone enough to warrant spending out on special tyres???

- not being funny btw, just curious..

Last year we had lots of snow and ice and I live at the bottom of a steep hill. The prius was pretty good at getting about, but it did have new tyres. Now the tyres are 17K miles on and I also do a lot of miles up to the midlands and into east sussex (where they get snow and ice too). So this year i was looking at putting some wet/winter tyres on rather than risk sliding about on the not so new normal tyres. I also pop over to France/Belgium although have not hit snow and ice there for some years.

But yes, down in the deepest south we don't get a lot of snow (normally) but last week we had -ve temps in the morning so a chance of early morning black ice already.

[Jan&tone]

Johal -oic... Just wondered as my parents lived over the water on the island for many years and never saw any snow!