A Question About Performance Tyres? Ask The Michelin Expert!

[Lexus Owners Club]

Michelin have kindly agreed to be available to answer all your questions on tyres.

"Ask the Expert" will run from Monday 10th November until Friday 5th December.

Lexus Owners Club are pleased to announce that we have managed to acquire the services of Jamie McWhir, Michelin UK Technical Manager, for our "Ask The Expert" thread on tyres.

So if it's a question on tyre pressures, tyre choice, tyre ratings, tyre wear, mixing tyres, brands, Super sports, Cup 2's, Primacy 3's, Pilot Sport 3's or just about anything and everything tyre related then please ask away ... :)

Questions will be answered by Jamie McWhir, Michelin UK Technical Manager

Profile: Jamie McWhir, Michelin UK Technical Manager

Career Highlights:

- Worked in the Michelin motorsport team with the BTCC and Vauxhall 888 from 1997 to 2000

- F1 Race Engineer for Michelin, France with the Renault F1 team, working with Alonso, Button, Fisichella, Trulli, McNish & Webber

- Masters Degree in Motorsport Engineering at Cranfield t

- Tyre Support Engineer, Red Bull Racing in 2007-2009

- Now Michelin Technical Manager, UK , responsible for Car, Van & 4x4 tyres

"Ask the Expert" begins on Monday 10th November...

[ALLISTER1965]

Hi Jamie,

I currently have a 2012 RX450h and I keep hearing everywhere that it's going to be a really bad winter this year.

In your opinion, do you think that winter tyres are really worth the money, especially on a large 4wd SUV like the RX? Obviously on this car it's going to cost me quite a bit for winter tyres so I just want to be sure it will be money well spent before I take the plunge?

Cheers

[Lexus Phil]

I'm also interested in the benefits of winter tyres. Especially with the 220d being rear wheel drive....

[jumbojake]

I have the same question.... for an IS200d ....

Is winter tyres worth it, or better just to get a set of chains to use with normal good quality 'wet road' tyres

I hear winter tyres are not very good for wet/dry roads, which is 99% of the time

[Wotan2666]

Hey Jamie McWhir i have a question what size is good for winter tires when my sommer tires are 225/45 R17 i heard its better then they are not wo wide but thicker, and what tire do u recommend for icy roads when i got RWD.

[RayKhan]

I have a totally different question

Have you got any nice Michelin Stickers that I can put round my Scalextric Track?

Will let you come have a drive if you like!

[DougCF72]

For many years now, some garages have advised to only fit a new pair of tyres to the rear of the car irrespective of the driven wheels ?

The reason they give is that the majority of tyre failures happen with "rear" tyres - and because of that - most drivers will have a bigger problem controlling oversteer than ( say) aquaplaning...........!!!!!

For me, having driven for 50 years, having had many tyre failures on different cars, I have never had a problem with oversteer, but I have frequently had "moments" with unexpected aquaplaning, when my front tyres were not the best on the car ??

Doug Symmons, Cardiff, UK

[jumbojake]

regarding new tyres on rear axle...... 5th Gear did a test on this ... the results were pretty scary and proved the rear axle should always have the best tyres.

[Jamie McWhir]

Hi Jamie,

I currently have a 2012 RX450h and I keep hearing everywhere that it's going to be a really bad winter this year.

In your opinion, do you think that winter tyres are really worth the money, especially on a large 4wd SUV like the RX? Obviously on this car it's going to cost me quite a bit for winter tyres so I just want to be sure it will be money well spent before I take the plunge?

Cheers

Hi Allister

Winter tyres were a bit of a mystery to me prior to living in France, but really after the first time I used them in the winter, I've been a convert, as have been most of my family and friends. Once you have them in the cold and wet and snow, they are a huge benefit. To some extent give me a 2wd on winter tyres on a cold day over a 4wd on summer tyres.

The main benefits are the compounds are designed for lower temperature ranges. They aren't like an "on/off" switch, but they will remain supple from -20 all the way up through to summer temps, where a summer tyre compound will start to stiffen as it cools. Meaning the winter tyre will give you more grip as it will key into the surface and give the macroscopic bonds the ability to form with the road surface. The tread patterns are also different to claw into snow and ice.

Our tyres have compounds for a "european" winter (we sell others for a harsher "nordic/siberian" winter), meaning that the whole range of winter conditions will be covered.

If you are keeping your RX for a while, you have a few options. go summer/winter with the same size, or what I would do is buy a second set of wheels in a smaller size (what's your options..) as the tyres will be cheaper, and this also keeps your summer wheels free from the salt and grit off the roads. Plus you save yourself £200 a year swapping tyres over. If you have the car over 2-3 years, you won't spend anymore money on tyres/wheels but running a second set (which is the common way of doing it on the continent)

if you want anymore help with sizes or a specific recommendation let me know.. oh.. ps.. don't wait til it snows as the small supply of winter tyres will have disappeared by that point if you are going to do it , plan now..

[Jamie McWhir]

I have the same question.... for an IS200d ....

Is winter tyres worth it, or better just to get a set of chains to use with normal good quality 'wet road' tyres

I hear winter tyres are not very good for wet/dry roads, which is 99% of the time

I owned a 330d E46 a few years back and ran 17" winter tyres on it every year.

As a rear wheel drive it was rubbish in the snow, especially with wider rear tyres.

No, I wouldn't use chains or socks, as they really are only a "get out of trouble" option.

Winter tyres are better significantly over summer tyres on a cold wet road, as the compounds and pattern are more efficicient.

At around 5-7 celcius (and below, e.g. October to March/april), braking from 50km/h (~30mph) you gain a car length in braking on winter tyres.

If you end up being unlucky enough to come across an ambulance in the UK, most of them will be wearing our winter tyres.

There are loads of options for the 220d, but as I said in the post above, you can go same size or smaller wheels and a second set..

[jumbojake]

thanks for the quick reply.... would you recommend just changing rear tyres? (wheel & tyre is getting bit pricey!)

[Jamie McWhir]

Hey Jamie McWhir i have a question what size is good for winter tires when my sommer tires are 225/45 R17 i heard its better then they are not wo wide but thicker, and what tire do u recommend for icy roads when i got RWD.

Hi

It depends where you are, but the 220d could run the 225/45-17 or 205/55-16 (obviously on other wheels...)

If you aren't in russia or scandanavia, go with Michelin Alpin Range, (the tyres for the other countries are X-Ice North)

[Jamie McWhir]

thanks for the quick reply.... would you recommend just changing rear tyres? (wheel & tyre is getting bit pricey!)

Absolutely not..

It will massively unbalance the car. We have done testing with it, and the cars are very difficult to handle as you would end up with traction and no steering.. Imagine going outside with a wellie on one foot and a trainer on the other..

Think about a second hand set of winter wheels. As the difference in tyre prices 17" to 16" could be enough to pay for the wheels. Plus you end up with a set of wheels that will mean you don't wear your summer tyres out over the winter!

[Jamie McWhir]

I have a totally different question

Have you got any nice Michelin Stickers that I can put round my Scalextric Track?

Will let you come have a drive if you like!

what kind of size??

[ALLISTER1965]

Hi Jamie,

I currently have a 2012 RX450h and I keep hearing everywhere that it's going to be a really bad winter this year.

In your opinion, do you think that winter tyres are really worth the money, especially on a large 4wd SUV like the RX? Obviously on this car it's going to cost me quite a bit for winter tyres so I just want to be sure it will be money well spent before I take the plunge?

Cheers

Hi Allister

Winter tyres were a bit of a mystery to me prior to living in France, but really after the first time I used them in the winter, I've been a convert, as have been most of my family and friends. Once you have them in the cold and wet and snow, they are a huge benefit. To some extent give me a 2wd on winter tyres on a cold day over a 4wd on summer tyres.

The main benefits are the compounds are designed for lower temperature ranges. They aren't like an "on/off" switch, but they will remain supple from -20 all the way up through to summer temps, where a summer tyre compound will start to stiffen as it cools. Meaning the winter tyre will give you more grip as it will key into the surface and give the macroscopic bonds the ability to form with the road surface. The tread patterns are also different to claw into snow and ice.

Our tyres have compounds for a "european" winter (we sell others for a harsher "nordic/siberian" winter), meaning that the whole range of winter conditions will be covered.

If you are keeping your RX for a while, you have a few options. go summer/winter with the same size, or what I would do is buy a second set of wheels in a smaller size (what's your options..) as the tyres will be cheaper, and this also keeps your summer wheels free from the salt and grit off the roads. Plus you save yourself £200 a year swapping tyres over. If you have the car over 2-3 years, you won't spend anymore money on tyres/wheels but running a second set (which is the common way of doing it on the continent)

if you want anymore help with sizes or a specific recommendation let me know.. oh.. ps.. don't wait til it snows as the small supply of winter tyres will have disappeared by that point if you are going to do it , plan now..

Thanks Jamie much appreciated. I think I will start looking around for a second set of wheels as I'm planning to keep the RX for at least another couple of years :)

[Jamie McWhir]

For many years now, some garages have advised to only fit a new pair of tyres to the rear of the car irrespective of the driven wheels ?

The reason they give is that the majority of tyre failures happen with "rear" tyres - and because of that - most drivers will have a bigger problem controlling oversteer than ( say) aquaplaning...........!!!!!

For me, having driven for 50 years, having had many tyre failures on different cars, I have never had a problem with oversteer, but I have frequently had "moments" with unexpected aquaplaning, when my front tyres were not the best on the car ??

Doug Symmons, Cardiff, UK

Doug

It's really two different mechanisms in place.

Aquaplaning is purely down to the tyre not having sufficient tread depth to cope with the water depth. Which basically lifts the tyre off the road and it floats along on the film of water. So it can affect the front or rear equally. Yes, with lower front tread depths as the front tyres always hit the water first, you'll experience aquaplaning first on that axle. However, you don't tend to get much aquaplaning until your tyres are close to 1.6-2mm. E.g. virtually dead. However, our data shows that when accidents happen in the wet, the majority are on roads with very little water depth, ~0.5-1mm.

Hence the main mechanism happening on wet road accidents isn't aquaplaning, its pure lack of grip.

So with new tyres to the rear, all you are doing is giving the rear axle more grip potential. So the car will more likely understeer. Which is always a more benign balance. Oversteer is harded to correct and less progressive, plus cars are designed primarily to be either neutral or slightly understeery, as its the most easy balance to correct.

Having tested new fronts or new rears for years, I'd always fit new tyres to the rear.

Garages don't tend to do it, as most modern cars are FWD, hence wear front tyres out quicker, and swapping tyres and wheels around in the workshop just takes time...

As the tyre isn't in contact with the road, it just lifts.. that's why aquaplaning it scary.

[Captain Fizz]

With regards to Winter tyres on the IS 250 / 220D...

From Door panel on mine (for reference)...

205/55/R16 is what's recommended.

I worked this out to be 6.5 to 7J x 16" wheels, Offset of 40~45 with 5 x 114.3 for the bolts if getting wheels for it.

(Sorry to intrude, just a few peeps were asking :) )

Still looking at £200 - £600 depending on good auctions to brand new.

[Jamie McWhir]

With regards to Winter tyres on the IS 250 / 220D...

From Door panel on mine (for reference)...

205/55/R16 is what's recommended.

I worked this out to be 6.5J x 16" wheels, Offset of 40~45 with 5 x 114.3 for the bolts if getting wheels for it.

(Sorry to intrude, just a few peeps were asking :) )

Still looking at £200 - £600 depending on good auctions to brand new.

ok..

Fellow scotsman being devils advocate about money.. (I'm basing this on my experience running winters on a 330d E46 BMW..)

Second hand alloys from eBay £150

Four 17" 225/45-17 Winter tyres £450 (If I'd bought them without my discount...)

So £600 invested. Tyres rotated front to rear each year. Did 4 seasons and virtually 30K so £150 a winter

18" Summers would have been £125 each for fronts £200 for rears. So the fact that over that 30K i ran the winters I didn't wear any summer tyres out, there's £650 saved

Plus the reduced likelyhood of an accident (no costs of insurance excess) and the fact the car was never immobile in heavy snow, (what value is that?)

Plus two separate occasions on taking the summers off I noticed a nail that I could then repair, possibly saving a dead tyre..

So yes, I don't deny that it's a cost. But while it might be a cost up front, then it pays back if you have the car a year or two.

I would always say that the winter alloys don't need to look mint, as they are only going ot get covered in salt and grit anyway..

205/55-16 Winters vs. 225/45-17 Winters, a quick cost comparison.. £90 vs. £120.. so almost enough to buy a set of wheels with the saving.

Yes, its an expense. If you are selling the car in the next year.. don't do it.. but there are ways to do it..

eBay is a great place to look, as you may find someone who's had a set and doesn't have the car is now selling them on..

[Animal Mother]

Jamie

What is your advice on storing your winter/summer tyres when the other tyres are fitted:

Inside or outside?

Inflated or deflated?

On their sides or ends (you know what I mean)?

On wheels or off wheels?

[Jamie McWhir]

Jamie

What is your advice on storing your winter/summer tyres when the other tyres are fitted:

Inside or outside?

Inflated or deflated?

On their sides or ends (you know what I mean)?

On wheels or off wheels?

Ok

Ideally stored inside, in a stable temperature away from direct sunlight or harsh UV lights. E.g. if they are in the shed and you've a window, cover them with something

If you have them on wheels they don't need stripped

Stack them flat on their inside sidewall (e,g, wheel face up)

If you stack them as all 4, I'd invert the stack once every 3-4 months (so the bottom tyre isn't loaded all the time.. to be fair even I sometimes forget to get round to that)

You can also store them on a rack (as opposed to just on the floor)

Other important thing for tyres is away from a direct heat source and away from any chemicals and solvents (e.g. not next to the petrol can for your lawnmover..)

You can get for around £20-30 sets of "tyre blankets" that look like the motorsport ones, but are marked with the tyres position so you can store them that way (search on eBay or amazon...)

[LexiMarc]

Jamie,

Is it really worth getting tyres filled with Nitrogen? Are the minor benefits worth the inconvenience of not being able to use normal air?

[Jamie McWhir]

Jamie,

Is it really worth getting tyres filled with Nitrogen? Are the minor benefits worth the inconvenience of not being able to use normal air?

Hi

In a word, no..

When we were in F1 (oh those glorious heady days...) we used ultra dry air.

The only benefits of nitrogen are that pure nitrogen tends to be dry (so you remove any small amount of water vapour from the gas used), however if the garage has a decent drier on their compressor it will be fairly dry.

And that the molecules themselves are larger, hence diffuse slower through the polymer of the rubber. So you will maintain pressure slightly better. All modern tyres have a butyl liner anyway, so this tends to be the difference between slow and very slow..

Plus the air we breathe is ~80% nitrogen anyway. If it's free then maybe there is a small benefit.. but I always use air.. If it's good enough for Fernando Alonso, it's good enough for me!

[LexiMarc]

Jamie,

Is it really worth getting tyres filled with Nitrogen? Are the minor benefits worth the inconvenience of not being able to use normal air?

Hi

In a word, no..

When we were in F1 (oh those glorious heady days...) we used ultra dry air.

The only benefits of nitrogen are that pure nitrogen tends to be dry (so you remove any small amount of water vapour from the gas used), however if the garage has a decent drier on their compressor it will be fairly dry.

And that the molecules themselves are larger, hence diffuse slower through the polymer of the rubber. So you will maintain pressure slightly better. All modern tyres have a butyl liner anyway, so this tends to be the difference between slow and very slow..

Plus the air we breathe is ~80% nitrogen anyway. If it's free then maybe there is a small benefit.. but I always use air.. If it's good enough for Fernando Alonso, it's good enough for me!

Thanks for that I had a feeling it was a bit of a sales gimmick at some tyre places!

[CharlieSC430]

Jamie,

What's your advice in relation to run flat tyres? I like the idea of them in some ways but I'm currently running them on my SC430 and I'm convinced they definitely make the ride too firm (by Lexus standards anyway). I've seen some other members in the past have switched to normal tyres with supposedly good results. Are there any negatives to doing this aside from not having a spare? Also, is the foam stuff any good in emergencies? Obviously it won't be in a complete blow out....

[Jamie McWhir]

Jamie,

What's your advice in relation to run flat tyres? I like the idea of them in some ways but I'm currently running them on my SC430 and I'm convinced they definitely make the ride too firm (by Lexus standards anyway). I've seen some other members in the past have switched to normal tyres with supposedly good results. Are there any negatives to doing this aside from not having a spare? Also, is the foam stuff any good in emergencies? Obviously it won't be in a complete blow out....

Ok..

Few things. Run Flats should really only go on vehicles with run flat wheels as the hump for the bead seat is slightly different, to improve bead retention under pressure loss..

99% of Run flat's on the market are used on cars that left the factory on them, primarily BMW, Mini and Mercedes. In the past they have traditionally been heavier and less compliant and supple. Hence have often worn unevenly, been worse for grip and rolling resistance and the comfort of the tyre (as part of the unsprung suspension of the car) has been the worst complaint.

Now things are changing a bit. I can only really talk about our ranges in depth, but I know we aren't totally alone. Our 2014 new runflats are thinner, lighter and perform like a standard tyre. So things are changing.

It's individual choice. I wouldn't buy a run flat, if I had the choice, however, loads of people drive run flat equipped cars..

As for the temporary repair solutions they all have they're pluses and minuses. The most important thing to bear in mind is they are all just a get you home or to a garage. They have benefits, but get the tyre checked asap, as often the damage is internal and you can't see it..