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crocodile tears

755 posts

34 months

[news] 
Tuesday 8th May 2012 quote quote all
Nigel_O said:
AnotherGareth said:
What will you be doing if lift-off isn't the cause of the oversteer?
Unlikely, in a FWD car.
I've had it more times than I can remember on an fwd car... decent tires on the front and decidedly average tires on the back.. wet corner near the front limit of grip and you will have the back end breaking away with or without lift off.

Nigel_O

Original Poster:

414 posts

107 months

[news] 
Tuesday 8th May 2012 quote quote all
Must be my choice of car then, as I've never had the back end break away, even with new fronts and the rears on the wear bars

AnotherGareth

168 posts

62 months

[news] 
Wednesday 9th May 2012 quote quote all
Nigel_O said:
Must be my choice of car then
More likely is that you are a cautious driver. Possibly you have enough experience of powerful rwd cars to have learned delicacy of inputs so as to not be taking liberties in powerful fwd cars?

Nigel_O

Original Poster:

414 posts

107 months

[news] 
Wednesday 9th May 2012 quote quote all
AnotherGareth said:
More likely is that you are a cautious driver. Possibly you have enough experience of powerful rwd cars to have learned delicacy of inputs so as to not be taking liberties in powerful fwd cars?
I'm cautious when in the presence of other road users - I take the view that everyone else on the road is a potential idiot and out to get me - that way I'm rarely surprised by another driver's actions.

However, when the opportunity arises, I'm far from cautious. I enjoy finding the limits of traction - I find it edicational as well as fun. As well as trophies for safe driving (from road safety trials) I also have trophies from hillclimbing and I've won the FWD handling discipline at Ten of the Best twice in the last six years (came second twice too).

I certainly have no fear of driving at (or just beyond) the limits of a car when the conditions allow (which clearly is extremely rare on the public highway). However, for whatever reason, I struggle to make my car oversteer for any other reason than lifting off or braking halfway round a slippery bend. In the dry, it'll get a bit squirmy when provoked, but I've only ever lost the rear end once in the dry (made the mistake of trying to change gear while flat in second gear around a long left-hander - the tank-slapper than ensued was fairly spectacular - I hit the lock stops in both directions trying to save it - which I ultimately failed to do...)

As for RWD, I'm crap. I've never liked power oversteer. This is partly down to the fact that the only RDW cars I've ever owned were a Chrysler 180 (yes, I was the one..) a Sierra 1.8 and a Ferrari F355. The later was spectacularly quick round the bends and hugely enjoyable to drive at anything up to 9/10, but I never really got near its limits for fear of interfacing with the scenery. I already know at this point that when a mid-engined car starts to spin, its generally difficult to get it back - I once managed to spin it in a straight line on the brakes (changed down too early on a slippery wet track and locked the rears)

Back on topic, are there really any FWD cars around that are so prone to oversteer that you're best advised to put new tyres on the back, or are the "gurus" just working to the lowest common denominator and advising everyone to do it, just in case?....

S. Gonzales Esq.

1,972 posts

100 months

[news] 
Wednesday 9th May 2012 quote quote all
Am I getting the wrong end of the stick here?

I thought the point (as shown in the video I linked to earlier) is that having deeper tread on the front makes the rear tyres more likely to aquaplane on wet corners.

Aquaplaning is when the tread can't clear water fast enough so the tyre ends up with a layer of water between it and the road, resulting in zero grip. This loss of grip is sudden, and not the same thing as the gradual break-away you get with a tyre on a dry road.

Am I the only one thinking that the posters talking about dry grip have missed the point of this advice entirely?
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_Neal_

1,282 posts

107 months

[news] 
Wednesday 9th May 2012 quote quote all
I think the received wisdom (backed up by the articles) makes sense - we're talking about wet grip, and the liklihood of surprise (not intentional) lift off oversteer, in the course of road (not track) driving. I don't want to be trying to control lift-off-oversteer on the road, and more tread depth on the rears does seem to help.

I don't recall my 20vt coupe having any tendency towards lift-off oversteer at all - it handled well, and just understeered at the limit. I used to put new tyres on the rear of that car and rotate the rears to the front - I've never had a car that wore it's rear tyres so lightly (or its fronts so heavily) so rotating them in that direction made sense, otherwise you just end up with brand new fronts and 5-year-old rears still with 5+ mm of tread! I didn't track the car though.

Also, Nigel, it sounds like you need a powerful front-engined RWD car in your life.

Nigel_O

Original Poster:

414 posts

107 months

[news] 
Wednesday 9th May 2012 quote quote all
S. Gonzales Esq. said:
I thought the point (as shown in the video I linked to earlier) is that having deeper tread on the front makes the rear tyres more likely to aquaplane on wet corners.


Am I the only one thinking that the posters talking about dry grip have missed the point of this advice entirely?
This is the point (or at least part of it). Let's create a pair of scenarios, based on a FWD car that has worn-out front tyres and half-worn rear tyres (surely an incredibly common occurence in the FWD community)

Scenario 1

Owner listens to perceived wisdom and fits the new tyres on the rear and transfers the half-worn rears to the front.

IMHO, aquaplaning will onset much earlier, becuase the tyres that are doing the majority of the water clearance will be the half-worn jobbies now on the front. The tyres with the greatest tread depth are not having to do very much at all.

Scenario 2

Owner fits the new tyres on the front and leaves the part-worns on the rear. The new front tyres will therefore clear the vast majority of the water, leaving the rears with only a little water clearance to do.

If the part-worn rears are THAT worn that they will still aquaplance after the fronts have cleared a path, then they shouldn't be on the car anyway.

And as for dry grip - you're right - it's irrelevant, as a worn tyre probably has more grip than a new one (which I think I mentioned in the original post, or soon after)

Speedy11

443 posts

96 months

[news] 
Wednesday 9th May 2012 quote quote all
Nigel_O said:
Scenario 2

Owner fits the new tyres on the front and leaves the part-worns on the rear. The new front tyres will therefore clear the vast majority of the water, leaving the rears with only a little water clearance to do.

If the part-worn rears are THAT worn that they will still aquaplance after the fronts have cleared a path, then they shouldn't be on the car anyway.

And as for dry grip - you're right - it's irrelevant, as a worn tyre probably has more grip than a new one (which I think I mentioned in the original post, or soon after)
Thats all very well but when going around a corner the rear tyres take a slightly different path to the front.



Nigel_O said:
If the part-worn rears are THAT worn that they will still aquaplance after the fronts have cleared a path, then they shouldn't be on the car anyway.
New tyres have about 8mm of tread while the legal limit which I would say most people go down to and maybe below is 1.6mm which can give a difference of 6.4mm between the new fronts and worn rears which no amount of path clearing will make up for.

Which is why it is simpler and safer to say to the general public that new tyres should go on the rear.

Edited by Speedy11 on Wednesday 9th May 17:00

Nigel_O

Original Poster:

414 posts

107 months

[news] 
Wednesday 9th May 2012 quote quote all
Speedy11 said:
Thats all very well but when going around a corner the rear tyres take a slightly different path to the front.
Yes, but the difference at road speeds is tiny and irrelevant - certainly at speeds where aquaplaning is a danger, the rear tyres will essentially follow in the tracks of the fronts.

Check it out next time you're driving in the rain - when you're following a car round a bend at anything over 30mph, there will be a single pair of tracks in the water. This is because the steering angle required to navigate bends in the road (as opposed to corners or junctions) is actually pretty small - probably less than a quarter of a turn of the steering wheel

crocodile tears

755 posts

34 months

[news] 
Wednesday 9th May 2012 quote quote all
Nigel_O said:
S. Gonzales Esq. said:
I thought the point (as shown in the video I linked to earlier) is that having deeper tread on the front makes the rear tyres more likely to aquaplane on wet corners.


Am I the only one thinking that the posters talking about dry grip have missed the point of this advice entirely?
This is the point (or at least part of it). Let's create a pair of scenarios, based on a FWD car that has worn-out front tyres and half-worn rear tyres (surely an incredibly common occurence in the FWD community)

Scenario 1

Owner listens to perceived wisdom and fits the new tyres on the rear and transfers the half-worn rears to the front.

IMHO, aquaplaning will onset much earlier, becuase the tyres that are doing the majority of the water clearance will be the half-worn jobbies now on the front. The tyres with the greatest tread depth are not having to do very much at all.

Scenario 2

Owner fits the new tyres on the front and leaves the part-worns on the rear. The new front tyres will therefore clear the vast majority of the water, leaving the rears with only a little water clearance to do.

If the part-worn rears are THAT worn that they will still aquaplance after the fronts have cleared a path, then they shouldn't be on the car anyway.

And as for dry grip - you're right - it's irrelevant, as a worn tyre probably has more grip than a new one (which I think I mentioned in the original post, or soon after)
you're reading far too much into all the wrong things and the wrong scenarios.


Nigel_O said:
AnotherGareth said:
More likely is that you are a cautious driver. Possibly you have enough experience of powerful rwd cars to have learned delicacy of inputs so as to not be taking liberties in powerful fwd cars?
I'm cautious when in the presence of other road users - I take the view that everyone else on the road is a potential idiot and out to get me - that way I'm rarely surprised by another driver's actions.

However, when the opportunity arises, I'm far from cautious. I enjoy finding the limits of traction - I find it edicational as well as fun. As well as trophies for safe driving (from road safety trials) I also have trophies from hillclimbing and I've won the FWD handling discipline at Ten of the Best twice in the last six years (came second twice too).

I certainly have no fear of driving at (or just beyond) the limits of a car when the conditions allow (which clearly is extremely rare on the public highway). However, for whatever reason, I struggle to make my car oversteer for any other reason than lifting off or braking halfway round a slippery bend. In the dry, it'll get a bit squirmy when provoked, but I've only ever lost the rear end once in the dry (made the mistake of trying to change gear while flat in second gear around a long left-hander - the tank-slapper than ensued was fairly spectacular - I hit the lock stops in both directions trying to save it - which I ultimately failed to do...)

As for RWD, I'm crap. I've never liked power oversteer. This is partly down to the fact that the only RDW cars I've ever owned were a Chrysler 180 (yes, I was the one..) a Sierra 1.8 and a Ferrari F355. The later was spectacularly quick round the bends and hugely enjoyable to drive at anything up to 9/10, but I never really got near its limits for fear of interfacing with the scenery. I already know at this point that when a mid-engined car starts to spin, its generally difficult to get it back - I once managed to spin it in a straight line on the brakes (changed down too early on a slippery wet track and locked the rears)

Back on topic, are there really any FWD cars around that are so prone to oversteer that you're best advised to put new tyres on the back, or are the "gurus" just working to the lowest common denominator and advising everyone to do it, just in case?....
Depends on car, tires/road, driver and perception of 'the limit'

I drive a stripped 306 gti-6 btw and with tires that arent great on the rear - it genuinely will break traction at the back without a lift off in some circumstances. I use to feel a tad nervous in the wet in high speed corners that the back would break away with visions of spinning out (as you could feel it slightly and as it was genuinely a possibility.)

At the end of the day its up to you.. Only you know how you drive and whether you prefer understeer, oversteer at the limit or whether you will reach the limit.


One thing I will tell you about aquaplaning though, I would rather have the best tires on the back - who cares about 'dispersing' water straight lines with the front tires, its the corners you should be worrying about.

Edited by crocodile tears on Wednesday 9th May 17:15

S. Gonzales Esq.

1,972 posts

100 months

[news] 
Wednesday 9th May 2012 quote quote all
If you watch the video (skip to 1m30s if you're in a rush), you'll see that in a similar situation to the one that you describe, the two cars behave quite differently.

The one with better tyres on the rear is understeering mildly, which the driver can correct easily by steering more or slowing down.
The one with better tyres on the front is an oversteering handful, ready to spit the car off the road.

This is happening at THE SAME SPEED. Where's the benefit in having better ones on the front?

Edited by S. Gonzales Esq. on Saturday 29th September 23:06

Nigel_O

Original Poster:

414 posts

107 months

[news] 
Wednesday 9th May 2012 quote quote all
@ crocodile tears - to be fair, a 306 has a propensity to turn around even with good tyres on it - one of the pointiest FWD cars I've ever driven. It must be scary in the wet with iffy rubber on the rear.

I'm finding it harder to argue against the "new on the rear" assertion. Maybe I've been lucky with my cars, or my chosen setup, or maybe I never let my rear tyres get so worn that there's a chance they'll aquaplane (although I still maintain that the rear tyres MUST have less water to clear, straight line OR corner, simply because they're following in the tracks of the fronts).

Perhaps this is the issue - it's not the fact that the rear tyres will aquaplane, it's the fact that the fronts won't - there's a big imbalance in wet grip so that the rear end will always let go before the rear, even if they're following in the wheeltracks of the fronts.

GravelBen

11,461 posts

118 months

[news] 
Thursday 10th May 2012 quote quote all
As I mentioned earlier there will be a certain specific window of water depth/speed combinations where one end will aquaplane and the other won't. Beyond this both ends will aquaplane, most likely the front first because it hits the deeper water first.

Maybe your roads are different to mine, but I can't think of anywhere in the real world where my approach to a large amount of standing water would be to hold a long, constant radius turn while gradually increasing speed until one end aquaplanes.

How often do you find yourself aquaplaning anyway?

powerstroke

2,910 posts

48 months

[news] 
Thursday 10th May 2012 quote quote all
GravelBen said:
As I mentioned earlier there will be a certain specific window of water depth/speed combinations where one end will aquaplane and the other won't. Beyond this both ends will aquaplane, most likely the front first because it hits the deeper water first.

Maybe your roads are different to mine, but I can't think of anywhere in the real world where my approach to a large amount of standing water would be to hold a long, constant radius turn while gradually increasing speed until one end aquaplanes.

How often do you find yourself aquaplaning anyway?
Exactly...

Orillion

130 posts

53 months

[news] 
Thursday 10th May 2012 quote quote all

powerstroke

2,910 posts

48 months

[news] 
Thursday 10th May 2012 quote quote all
Orillion said:
Looks like he lost vision when he hit the puddle, and turned in too much or harshly and was going a little fast as a result unballanced the car causing it to spin out...

Munter

25,428 posts

129 months

[news] 
Thursday 10th May 2012 quote quote all
GravelBen said:
As I mentioned earlier there will be a certain specific window of water depth/speed combinations where one end will aquaplane and the other won't. Beyond this both ends will aquaplane, most likely the front first because it hits the deeper water first.

Maybe your roads are different to mine, but I can't think of anywhere in the real world where my approach to a large amount of standing water would be to hold a long, constant radius turn while gradually increasing speed until one end aquaplanes.

How often do you find yourself aquaplaning anyway?
Sounds like lots of motorway junctions that. Long curve, with standing water hidden somewhere around it, requirement to either maintain a high speed or slow down to avoid cars ahead.

The kind of place where people see a 50 sign and think it's just for trucks. They then barrel around it at 70, not realising it was 50 because your sight line doesn't give you enough time to stop on a curve at 70 if traffic is backed up, and maintain control. Add standing water and it only gets worse.

edward1

752 posts

154 months

[news] 
Thursday 10th May 2012 quote quote all
The first time I experience the stability control doing its stuff was due to old (and crap) tyres on the back of my 156 just after I had bought it. I had made a snap decision to avoid a queue and go off a different exit of a roundabout (after checking for traffic behind). I made a progressive change in the turn radius feeling the front just about starting to understeer and was comfortable with this, what I hadn't anticipated was the back suddenly wanting to play! I corrected just as the electronic nanny did the same as a result I stayed on the road but it was a little bit of a surprise.

Once aware that was how the car would behave I actually enjoyed it and you had to be close to the grip limit of the fronts before the back went wayward. My wife drove the car for at least a year through all weather with these tyres on the back as they just wouldn't wear out and never once had any unsettling moments as she would never be near enough the limit for it to happen and for everything else (straight line breaking, accelerating) I'd rather have the grip on the wheels doing most of the work.

Each to their own though. If you understand how the car will behave you can drive accordingly


noumenon

1,158 posts

92 months

[news] 
Friday 25th May 2012 quote quote all

IMHO, there are three scenarios to consider:
- tendency to understeer (tyres on the front help)
- tendency to oversteer (tyres on the rear help)
- ability to brake in a straight line (tyres on the front help)

Most of my near misses were when something unexpectedly appeared in front of me, generally in a straight line. So I place the ability to brake in a stright line first and foremost. Hence new tyres for the front please.

If you're driving fast enough to risk oversteer, you should have new tyres on all four corners. And if you're not comfortable with overseer, you should slow down in general and get more driver training.

Am I wrong?

AnotherGareth

168 posts

62 months

[news] 
Friday 25th May 2012 quote quote all
noumenon said:
Most of my near misses were when something unexpectedly appeared in front of me
noumenon said:
get more driver training.
I hope you are taking your own advice.
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