What depth do you change tyre?

DaveyDave · 26-09-2018 1:46pm #1

What thread depths do people change at?

I hear it's recommended to change at 2-3mm.

Am I correct in thinking If my tyres are rotated, the new ones will then go on the back, replacing the most worn tyres, they will then be rotated again in future so the newer ones end up on the front, and the back/older ones replaced again?

I've done about 13,500km. If they're rotated is it possible I'll need 4 new ones at the same time?

Front driver side: 4.9mm, front passenger: 4.4mm
Rear driver side: 6.4mm, rear passenger: 6.1mm

colm_mcm · 26-09-2018 1:59pm

I wouldn’t bother rotating them. Just replace the worn ones with new ones when it’s time.

coylemj · 26-09-2018 2:53pm

DaveyDave wrote: »

Am I correct in thinking If my tyres are rotated, the new ones will then go on the back, replacing the most worn tyres, they will then be rotated again in future so the newer ones end up on the front, and the back/older ones replaced again?

With a front wheel drive car, the bulk of the wear is on the front tyres. You can either rotate the tyres to even out the wear or treat the two axles separately and replace each pair when required. Rotating when the front tyres have less tread than the rear ones give you the benefit of better braking but continuous rotating on that basis means that you will end up having to replace all four tyres at the same time.

With a rear wheel drive car, you may get even wear all round so it's not worth your while rotating but it really depends on your driving and braking habits.

DaveyDave wrote: »

I've done about 13,500km. If they're rotated is it possible I'll need 4 new ones at the same time?

That's pretty much what happens when you rotate tyres - you end up with four tyres with the same tread depth so they all need replacing at the same time.

Stoolbend · 26-09-2018 9:10pm

I replace mine at 3mm.

The back Tyres last the same amount of time as 2 sets of front Tyres. So every second time I get Tyres I’ve to buy 4.

Don’t bother with rotating at all.

mickdw · 26-09-2018 9:17pm

I go through much more front tyres than rears. I don't rotate as sticking fresh tyres on the front regularly suits me fine.

I am guilty of running them to right to the wear limits too often. The behaviour over standing water when near wear limit is shocking so I must change sooner.

magentis · 26-09-2018 10:11pm

2.5mm.

Best tyres on the back of a fwd most important.

colm_mcm · 26-09-2018 10:18pm

magentis wrote: »

2.5mm.

Best tyres on the back of a fwd most important.

Can’t agree with that. The only time tyres on the back of a FWD car will be an issue is if they’re bald. Front end does all the work, and it’s very unlikely that a FWD car would oversteer due to rear tyres not having loads of tread. Understeer is far more likely and wear happens way more on the front, so I’d always put the best ones out front. Rears with 2.5mm aren’t going to catch you out.

nim1bdeh38l2cw · 26-09-2018 10:27pm

magentis wrote: »

Best tyres on the back of a fwd most important.

Surely not. Best tyres go on the driven wheels!?

magentis · 26-09-2018 10:28pm

colm_mcm wrote: »

Can’t agree with that. The only time tyres on the back of a FWD car will be an issue is if they’re bald. Front end does all the work, and it’s very unlikely that a FWD car would oversteer due to rear tyres not having loads of tread. Understeer is far more likely and wear happens way more on the front, so I’d always put the best ones out front. Rears with 2.5mm aren’t going to catch you out.

worn rears are much more dangerous than worn fronts on a fwd car.When a car with good rears brakes loose it is far more predictable.

magentis · 26-09-2018 10:31pm

A fwd car that breaks loose on standing water is far more recoverable with more grip to the rear.

colm_mcm · 26-09-2018 10:32pm

magentis wrote: »

worn rears are much more dangerous than worn fronts on a fwd car.When a car with good rears breaks loose it is far more predictable.

You just know you’ll be ploughing straight into something?

sundodger5 · 26-09-2018 10:32pm

here we go again

Jimmy. · 26-09-2018 10:34pm

When the wire is out on them.

magentis · 26-09-2018 10:36pm

Braking will reduce the load on the rear axle, making the rear tyres more likely to lose grip. Likewise, reducing power abruptly will transfer weight from the rear axle onto the front, again reducing rear tyre grip. The only way to counteract oversteer is to steer the front wheels out of the corner, in other words reduce steering angle. This is something which is counter-intuitive and difficult to do whilst maintaining control of the vehicle.

CONCLUSION
To give the best possibilities of a vehicle handling safely when fitting new tyres to a vehicle in pairs, it is advisable to fit the new tyres to the rear axle.

magentis · 26-09-2018 10:39pm

colm_mcm wrote: »

You just know you’ll be ploughing straight into something?

Speak for yourself.

nim1bdeh38l2cw · 27-09-2018 7:33am

Ah, a troll.

i57dwun4yb1pt8 · 27-09-2018 9:35am

2mil

always put stronger grip on the rear for a FWD car ,
many times ive seen and heard people lose the car on a wet roundabout mainly when they have new tyres on the front and worn on the rear.

if your fronts are worn , move the rears forward and put new ones on the rear .

or rotate every 10 k and replace all 4 at 2 mil .

Mr.David · 27-09-2018 9:52am

It depends.

Wet conditions - tyre performance vs tread depth is close to linear as the capacity of the tyre to pump water is the key factor

Dry conditions - very little drop off in performance down to a certain depth when it degrades much more quickly

CJhaughey · 27-09-2018 10:58am

Michelin are making a big thing about whole lifetime grip now, where the grip levels remain pretty much constant over the lifetime of the tyre, I can't see that this will be the same for standing water but Michelin are selling it as a safety and economy issue.
Linky

kerten · 27-09-2018 5:18pm

magentis wrote: »

Braking will reduce the load on the rear axle, making the rear tyres more likely to lose grip. Likewise, reducing power abruptly will transfer weight from the rear axle onto the front, again reducing rear tyre grip. The only way to counteract oversteer is to steer the front wheels out of the corner, in other words reduce steering angle. This is something which is counter-intuitive and difficult to do whilst maintaining control of the vehicle.

CONCLUSION
To give the best possibilities of a vehicle handling safely when fitting new tyres to a vehicle in pairs, it is advisable to fit the new tyres to the rear axle.

What you say is correct in isolation but it is not the only risk when it comes to lack of grip due to low tread depth in one axle

Assuming 4 tyres are still over the limit and not chinese plastics on a fwd car, fresh tyres in front axle will improve braking performance and grip at cornering(extra weight in front and fwd car means they are under more pressure than rears handling/grip wise). You will need those everyday vs car is oversteering on a corner because driver wanted take corner at limits.

That doesn't mean 2mm tread depth at rear axle doesn't introduce any risk. It is just tackling the risk with more likelihood first if you can't replace the 4 tyres at the same time.

Myself generally change tyres at 2-2.5 mm but generally buy tyres with good grip so reduced performance due to tread depth is still ahead of chinese tyres.

bazz26 · 27-09-2018 5:38pm

I find the effectiveness of run flat tyres deteriorates well before the minimum thread level of 1.66 mm. I changed my last rears at about 2.5 mm, you find the rear of the car starting to struggle for grip and start to kick out more.

ongarite · 27-09-2018 6:06pm

bazz26 wrote: »

I find the effectiveness of run flat tyres deteriorates well before the minimum thread level of 1.66 mm. I changed my last rears at about 2.5 mm, you find the rear of the car starting to struggle for grip and start to kick out more.

What tyre you recommend for rear RFT for F10?
Presume you have/had 19" 275/35 profile?

Have Michelin Primacy HP at the moment, think they have been superseded by Primacy 3?

Pkiernan · 27-09-2018 6:11pm

magentis wrote: »

2.5mm.

Best tyres on the back of a fwd most important.

Any drive train benefits from best tread/tyre at the rear.

bazz26 · 27-09-2018 8:08pm

ongarite wrote: »

What tyre you recommend for rear RFT for F10?
Presume you have/had 19" 275/35 profile?

Have Michelin Primacy HP at the moment, think they have been superseded by Primacy 3?

Have Goodyear Eagle F1 AS3 and cannot fault them, however they seem to have rocketed in price online lately for some unknown reason so might switch to the Primacy 3 when the time comes.

SBPhoto · 27-09-2018 8:18pm

Pkiernan wrote: »

Any drive train benefits from best tread/tyre at the rear.

I would not agree with you on that, i always put my best tyres on the front as i always had front wheel drive for the last 50yrs, never had a rear slip away from me yet.

Andrewf20 · 27-09-2018 9:26pm

I go down to the legal limit tbh unless the tyre grip goes downhill before then (happened with 1 set). I dont rotate.

grogi · 27-09-2018 9:59pm

colm_mcm wrote: »

Can’t agree with that. The only time tyres on the back of a FWD car will be an issue is if they’re bald. Front end does all the work, and it’s very unlikely that a FWD car would oversteer due to rear tyres not having loads of tread. Understeer is far more likely and wear happens way more on the front, so I’d always put the best ones out front. Rears with 2.5mm aren’t going to catch you out.

Controlling understeer is easy, oversteer is lethal to an average driver..

colm_mcm · 27-09-2018 10:37pm

grogi wrote: »

Controlling understeer is easy, oversteer is lethal to an average driver..

It’s also very rare. Just to be clear we’re talking about front wheel drive cars where the rear tyres aren’t new but aren’t bald or on very low levels of tread where front set is new

Vs

front wheel drive cars where the front tyres that aren’t new but aren’t bald or on very low levels of tread where rear set is new.

Jimmy. · 27-09-2018 11:56pm

This is turning into I’ve a bigger penis than yours argument.

_Brian · 28-09-2018 10:57am

Run them down to the wear blocks, isn’t that what they are there for ??

Isambard · 28-09-2018 11:10am

I don't believe in rotating the wheels, that way you have to replace all 4 at once. More manageable to replace one pair followed by the other pair at a later date.

creedp · 28-09-2018 12:19pm

Isambard wrote: »

I don't believe in rotating the wheels, that way you have to replace all 4 at once. More manageable to replace one pair followed by the other pair at a later date.

Normally follow this approach also .. easier to replace a pair at €300 that all 4 at €600!

Charles Babbage · 28-09-2018 12:23pm

creedp wrote: »

Normally follow this approach also .. easier to replace a pair at €300 that all 4 at €600!

Over a period of time you spend the same amount of money.

grogi · 28-09-2018 12:56pm

Jimmy. wrote: »

This is turning into I’ve a bigger penis than yours argument.

We're not at that stage yet. Posters are still using reasonable arguments...

grogi · 28-09-2018 12:57pm

creedp wrote: »

Normally follow this approach also .. easier to replace a pair at €300 that all 4 at €600!

When changing all four you'd get additional discount...

mikeecho · 28-09-2018 3:34pm

I run mine down to the blocks.. 1.6mm,
However BMW recommend changing at 4mm.

creedp · 28-09-2018 8:39pm

Charles Babbage wrote: »

Over a period of time you spend the same amount of money.

True but I get paid a fixed sum which has to cover everything else also. Easier to spread cost over more than one cheque. Each to their own!

Rodin · 28-09-2018 8:43pm

I rotate after a year. Change at two years.

martyc5674 · 28-09-2018 9:35pm

Charles Babbage wrote: »

Over a period of time you spend the same amount of money.

Not true.
Simple maths, if you replace when your front are worn... and your rears are for argument sake 50% worn and keep doing that, you’ll have chucked essentially a new pair of tyres in the bin for every 8 new tyres.
Now if you rotated them so they all were at the limit at the same time you’d avoid this.
I’d rather not let all 4 tyres close to the limit than 2 at a time so I tend to replace by axel and never bothered rotating, plus chances are you’d be putting unbalanced rears on the front.
On the other hand I regularly swap drivers and passenger seats to keep seat wear symmetrical.

colm_mcm · 28-09-2018 9:46pm

martyc5674 wrote: »

Not true.
Simple maths, if you replace when your front are worn... and your rears are for argument sake 50% worn and keep doing that, you’ll have chucked essentially a new pair of tyres in the bin for every 8 new tyres.
.

I don’t think anyone’s saying they throw away the perfectly good back tyres if the front ones are worn

sundodger5 · 29-09-2018 7:02am

mikeecho wrote: »

I run mine down to the blocks.. 1.6mm,
However BMW recommend changing at 4mm.

The wear bars are at 2mm. afaik so you are even safer than you thought

Pkiernan · 29-09-2018 7:09am

SBPhoto wrote: »

I would not agree with you on that, i always put my best tyres on the front as i always had front wheel drive for the last 50yrs, never had a rear slip away from me yet.

It is best practise to put the best tyres at the rear.

Google it, although it may seem counter intuitive, it's safer.

Jimmy. · 29-09-2018 7:38am

Pkiernan wrote: »

It is best practise to put the best tyres at the rear.

Google it, although it may seem counter intuitive, it's safer.

And what kind of car does google drive?

Pkiernan · 29-09-2018 8:40am

Jimmy. wrote: »

And what kind of car does google drive?

?

grogi · 29-09-2018 10:19am

Pkiernan wrote: »

It is best practise to put the best tyres at the rear.

Google it, although it may seem counter intuitive, it's safer.

It is similar story for an average driver driving 4WD vs 2WD in bad conditions.

Typically the 4WD seem better - during acceleration it is much less affected by the bad conditions. It is the same with the better tyres at the front - car will accelerate much better and handle better.

But it makes the driver feel overconfident about the available grip, while worse tyres at the front warn the driver much earlier.

StereoSound · 29-09-2018 11:16am

I don't measure them and never did in my life. If they look a bit baldy I'll change them.

Cee-Jay-Cee · 29-09-2018 4:58pm

magentis wrote: »

2.5mm.

Best tyres on the back of a fwd most important.

I’ve been driving FWD cars for 30yrs and have always fitted new tyres on the front. The argument that you don’t want the rear end sliding out is pure rubbish, I have never had the rear end slide out, accidentally even with worn rear tyres. The front tyres steer and drive the car, so why on earth would you fit worn tyres on the front on a FWD car?

I also have had several Subaru’s and do the same, new tyres on the front, worn on the rear.

Pkiernan · 29-09-2018 5:22pm

Cee-Jay-Cee wrote: »

I’ve been driving FWD cars for 30yrs and have always fitted new tyres on the front. The argument that you don’t want the rear end sliding out is pure rubbish, I have never had the rear end slide out, accidentally even with worn rear tyres. The front tyres steer and drive the car, so why on earth would you fit worn tyres on the front on a FWD car?

I also have had several Subaru’s and do the same, new tyres on the front, worn on the rear.

It's simple physics, not rubbish, but each to his or her own.

colm_mcm · 29-09-2018 5:45pm

The rear being more likely to oversteer in the case of an extreme change of direction is true.

You’re replacing that with the the increased likelihood of aquaplaning, increased stopping distances and increased understeering.

Isambard · 29-09-2018 9:57pm

with a fwd car, it doesn't really matter what the back end is doing so long as the front wheels pull the car the way it's meant to be going.

grogi · 30-09-2018 8:46am

Isambard wrote: »

with a fwd car, it doesn't really matter what the back end is doing so long as the front wheels pull the car the way it's meant to be going.

But how many drivers instead of the break would press the accelerator when they sense something goes wrong?

What depth do you change tyre?

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