Today I get rid of my runflats

[Scuzi]

Isn't the whole idea of an emergency stop stopping asap. As such by knowing the characteristics do you think 'I don't need to plant the stoppers yet because I know these babies'll grip'?

No, it's about getting an idea of stopping distances, seeing if there is any pull in a particular direction, how the ABS reacts to the new tyres and getting a feel for them.

By learning how they react it can improve your reactions as a driver in an emergency situation. Knowing if the tyres are going to grip if you turn the wheel whilst standing on the brake pedal is a start.

 

[DRZ]

Changing your tyres shouldn't introduce a pull in a particular direction

I think the point Dfhaii is making is why do you need an idea of stopping distances? Its not like you wait until the last possible moment to hit the brakes when an emergency situation develops. A knowledge of your stopping distances in an emergency-stop situation is needless.

 

[jamoor]

Whenever I fit new tyres and get a couple of hundred miles on them I like to go to a quiet industrial estate at night and do a bit of testing. Emergency stops amongst a few other things. Different tyres can react in very different manners in these circumstances and it's good roadmanship (is there such a word) to learn these characteristics as soon as you can.

indeed, good idea to see where the limits are.

 

[Scuzi]

Changing your tyres shouldn't introduce a pull in a particular direction

I think the point Dfhaii is making is why do you need an idea of stopping distances? Its not like you wait until the last possible moment to hit the brakes when an emergency situation develops. A knowledge of your stopping distances in an emergency-stop situation is needless.

It shouldn't introduce a pull in a particular direction but it could. Improper fitment, faulty tyre etc.

Knowing at what point the tyres give up grip is essential knowledge. Knowing whether or not you will have to steer around an obstacle is essential.

I don't buy the "stand on the pedal and hope" point of view. Knowing your car inside out makes you a better driver. If you know what to expect, there is less to take you by surprise and hence your actions can subsequently be adapted. If knowing how your car will react in a certain situation becomes second nature, you stand a better chance of better controlling the situation.

 

[Glaucus]

Whenever I fit new tyres and get a couple of hundred miles on them I like to go to a quiet industrial estate at night and do a bit of testing. Emergency stops amongst a few other things. Different tyres can react in very different manners in these circumstances and it's good roadmanship (is there such a word) to learn these characteristics as soon as you can.

Exactly, same if I change brake pads. They all handle different and you should find out how they handle and how they react in different situation.

If you don't you are being foolish imo.

Isn't the whole idea of an emergency stop stopping asap. As such by knowing the characteristics do you think 'I don't need to plant the stoppers yet because I know these babies'll grip'?

Yep and knowing how much grip you have can drastically reduce your stopping distance, especially if you haven't got abs.

 

[Gaijin]

I don't know why the 452's are suddenly becoming popular as they've never been properly tested in any decent tests and it all seems to stem from the fact someone once bought some for his 5 Series on the 5 Series forum in BMWLand thought 'THESE ARE GREAT LIKE INNIT' despite not being a tyre tester and now suddenly everyone is buying them becuase they are cheap.

I'll wait until there is a subjective test between them and the top brands before I'd consider fitting them. Some of the performance advantages from premium brand tyres never make themselves known until you one day need to stop quickly in an emergency situation. I'd rather not wait until then to find out that actually, 452's are not all that.

Indeed they are not. I have 452's up front. I'm not a fan of the performance or the wear rate.

 

[DRZ]

It shouldn't introduce a pull in a particular direction but it could. Improper fitment, faulty tyre etc.

Knowing at what point the tyres give up grip is essential knowledge. Knowing whether or not you will have to steer around an obstacle is essential.

I don't buy the "stand on the pedal and hope" point of view. Knowing your car inside out makes you a better driver. If you know what to expect, there is less to take you by surprise and hence your actions can subsequently be adapted. If knowing how your car will react in a certain situation becomes second nature, you stand a better chance of better controlling the situation.

I am not disagreeing on that front, I am saying that:

At 70mph on the motorway a lorry is blown over in front of you, giving you no way out. What POSSIBLE use does knowing how long it will take you to stop have?

If you need to stop as quickly as possible, you simply apply the brakes just as hard as you can without locking up. If you have ABS and you do lock up, you can still steer. Knowledge of your tyres is simply superfluous in this situation.

Without ABS, its a different story.

 

[Scuzi]

I am not disagreeing on that front, I am saying that:

At 70mph on the motorway a lorry is blown over in front of you, giving you no way out. What POSSIBLE use does knowing how long it will take you to stop have?

If you need to stop as quickly as possible, you simply apply the brakes just as hard as you can without locking up. If you have ABS and you do lock up, you can still steer. Knowledge of your tyres is simply superfluous in this situation.

Without ABS, its a different story.

That's one of a million different posible situations that can present itself on the road. I did not state that knowing stopping distance is only useful in an emergency stop situation.

 

[DRZ]

That's one of a million different posible situations that can present itself on the road. I did not state that knowing stopping distance is only useful in an emergency stop situation.

But stopping distances in anything other than an emergency stop situation is entirely down to how hard you apply the brakes and to a lesser extent the surface you are on. The actual friction provided by the tyres only becomes a problem when it comes time that you need 100.0% of the available traction. Which in other words is an emergency stop.

 

[Glaucus]

I am not disagreeing on that front, I am saying that:

At 70mph on the motorway a lorry is blown over in front of you, giving you no way out. What POSSIBLE use does knowing how long it will take you to stop have?

If you need to stop as quickly as possible, you simply apply the brakes just as hard as you can without locking up. If you have ABS and you do lock up, you can still steer. Knowledge of your tyres is simply superfluous in this situation.

Without ABS, its a different story.

And how much pressure do you apply before you lock up?
But there's many many reasons you should find the limit of tyres. Not just emergency stops. But general braking all the way up to the emergency. As well as handling. I always test braking before I hoon it around corners and find the handling limit. I like to know my car inside out and what it can and can't do.

But stopping distances in anything other than an emergency stop situation is entirely down to how hard you apply the brakes and to a lesser extent the surface you are on. The actual friction provided by the tyres only becomes a problem when it comes time that you need 100.0% of the available traction. Which in other words is an emergency stop.

Ands a perfect emergency stop you apply 99.9% of the available grip, to stop he fastest. if you haven't tested how do you remotely know where that is?
Abs is great but my understanding is it still stops you slower than a well applied brake.

 

[DRZ]

And how much pressure do you apply before you lock up?
But there's many many reasons you should find the limit of tyres. Not just emergency stops. But general braking all the way up to the emergency. As well as handling. I always test braking before I hoon it around corners and find the handling limit. I like to know my car inside out and what it can and can't do.

The point is over there -->

This isnt about knowing your car well, its about the statement that you NEED to know how long it will take you to stop in an emergency stop situation. The point that we are trying to make is that in an emergency stop situation knowing exactly how long it will take you to stop is not going to change one god damn thing.

 

[Glaucus]

The point is over there -->

This isnt about knowing your car well, its about the statement that you NEED to know how long it will take you to stop in an emergency stop situation. The point that we are trying to make is that in an emergency stop situation knowing exactly how long it will take you to stop is not going to change one god damn thing.

But you still said why do you need to know the limits?
A) so you don't make a non emergency stop into an emergency stop
B) when you do have an emergency stop, you have a good idea of how the car handles, brakes and tyre limits and a good idea of how hard to brake.

 

[DRZ]

This entire conversation started as a discussion solely about knowing the characteristics of your tyres during an emergency stop. The muddying of the waters by other posters aside, I stand by my point - in an emergency stop situation (ie any time you need to use all of the available traction) any competent driver would not change the outcome of the situation by knowing how long it will take them to stop.

 

[Scuzi]

But stopping distances in anything other than an emergency stop situation is entirely down to how hard you apply the brakes and to a lesser extent the surface you are on. The actual friction provided by the tyres only becomes a problem when it comes time that you need 100.0% of the available traction. Which in other words is an emergency stop.

You don't believe that learning how your car reacts when braking with new tyres is prudent? How soon do the wheels lock up? Can you get away with applying a greater or a lesser braking force before the wheels lock up or the ABS kicks in with the new tyres? I agree that an emergency stop is usually a matter of standing on the pedal until you stop but it isn't always. As I said before, braking is only one aspect of handling characteristics that can be changed by fitting new tyres. My posts have made this clear.

You're flogging a dead horse and arguing for the sake of it. You know as well as I do the point I am making and I sincerely hope your pedantry isn't with an ulterior motive.

I stand by my point - in an emergency stop situation (ie any time you need to use all of the available traction) any competent driver would not change the outcome of the situation by knowing how long it will take them to stop.

A completely moot point given that the discussion has progressed further.

 

[Glaucus]

This entire conversation started as a discussion solely about knowing the characteristics of your tyres during an emergency stop. The muddying of the waters by other posters aside, I stand by my point - in an emergency stop situation (ie any time you need to use all of the available traction) any competent driver would not change the outcome of the situation by knowing how long it will take them to stop.

No but they will change and adapt if they already know roughly where there tyre limits are, know how the car handles. A car handles and steers very differently under heavy braking. if you have knowledge of this. Then it can help you out in an emergency.

It actually started by me commenting on Fox saying he should know the limits before he gets into an emergency.

 

[DRZ]

You don't believe that learning how your car reacts when braking with new tyres is prudent? How soon do the wheels lock up? Can you get away with applying a greater or a lesser braking force before the wheels lock up or the ABS kicks in with the new tyres? I agree that an emergency stop is usually a matter of standing on the pedal until you stop but it isn't always. As I said before, braking is only one aspect of handling characteristics that can be changed by fitting new tyres. My posts have made this clear.

You're flogging a dead horse and arguing for the sake of it. You know as well as I do the point I am making and I sincerely hope your pedantry isn't with an ulterior motive.



A completely moot point given that the discussion has progressed further.

Note that earlier I said that I didnt disagree with knowing the limits of your car, I only disagreed with the notion that knowing how far you will go once at maximum braking power would somehow be a benefit.

I would also dearly, dearly love to know what on earth you meant by "I sincerely hope your pedantry isn't with an ulterior motive.". I am sat here with a smile discussing what I see to be a ludicrous assertion (limited specifically to what I mentioned just above). Are you sat there with your knickers in a twist over this?

 

[Glaucus]

What a load of ****! If you do, I bet you're about the only person on here who thinks, 'hmm, I've got me some new tyres, best test the emergency stop characteristics'

Perhaps you should learn and start doing it yourself. It's not just emergency stops. I learn everything about them. It's idiotic not to learn you cars abilitys. You never know what the road and others will throw at you so you should be prepared for everything. Why do piolts practice emergencys? Maybe because people who practice and know how it handles have a better chance of not crashing.

 

[Dfhaii]

I like how we've come back to my original post . What should I practice, emergency stops? Should I arrange for a plane to crash land in front of a train crash, while bomb disposal is going on by the side of the road so I know how I would react in that instance? Emergency stop - apply the brakes until you are stationary.

 

[Scuzi]

Note that earlier I said that I didnt disagree with knowing the limits of your car, I only disagreed with the notion that knowing how far you will go once at maximum braking power would somehow be a benefit.

Well, very good then. Why quote me when making the point? It appeares you were suggesting that I claimed that an emergency stop, and only an emergency stop in the scenario you concocted can be influenced by knowlege of how the car reacts.

I would also dearly, dearly love to know what on earth you meant by "I sincerely hope your pedantry isn't with an ulterior motive.". I am sat here with a smile discussing what I see to be a ludicrous assertion (limited specifically to what I mentioned just above). Are you sat there with your knickers in a twist over this?

No, I'm not. I don't get my knickers into a twist, love. It just isn't your style to nitpick and selectively argue, hence my suspicion.

 

[Glaucus]

I like how we've come back to my original post . What should I practice, emergency stops? Should I arrange for a plane to crash land in front of a train crash, while bomb disposal is going on by the side of the road so I know how I would react in that instance? Emergency stop - apply the brakes until you are stationary.

How about if you need to swerve? how do you know where the grip limit is?

What happens if you take a corner the same speed you use to and the new tyres don't have as much grip?

Just doing some simple to very hard braking in a quite area can tell you a lot and give you knowledge you may well need in an emergency.