Car Tyres

Iceweasel

The difference between oversteer and understeer is easy to explain.

With understeer you go straight on at a bend and the car enters the field front first.

With oversteer the rear of the car enters the field first.

:rotfl:

Joe_Horner

forgotmyname wrote: »

Its not just understeer and oversteer though, What about the the extra distance it takes to stop?

The difference will be marginal. If you do screw up enough to lock the front wheels (or engage the ABS) then you immediately get weight transferring to the back again, and the backs take up a big chink of the slack.

But, honestly, I've never come even close to locking the wheels in a car (except intentionally) in probably half a million miles by now. That includes cities, rural back roads, motorway and fast A roads, with everything in between. In sunshine, rain, snow, ice, fog, day, night........

Those nuns running out from behind baskets of kittens are a lot less common than some people seem to think. Anyone who keeps having them jump out should maybe be learning to think "Ahh, a basket of kittens, there might be a nun behind it!" which tends to remove the need for emegency braking.

nobbysn*ts

Joe_Horner wrote: »

The difference will be marginal. If you do screw up enough to lock the front wheels (or engage the ABS) then you immediately get weight transferring to the back again, and the backs take up a big chink of the slack.

But, honestly, I've never come even close to locking the wheels in a car (except intentionally) in probably half a million miles by now. That includes cities, rural back roads, motorway and fast A roads, with everything in between. In sunshine, rain, snow, ice, fog, day, night........

Those nuns running out from behind baskets of kittens are a lot less common than some people seem to think. Anyone who keeps having them jump out should maybe be learning to think "Ahh, a basket of kittens, there might be a nun behind it!" which tends to remove the need for emegency braking.

Boring driving?

Richard53

nobbysn*ts wrote: »

Boring driving?

Competent driving. If you keep locking your wheels up on a public road because you can't anticipate hazards, you need some more lessons.

nobbysn*ts

Richard53 wrote: »

Competent driving. If you keep locking your wheels up on a public road because you can't anticipate hazards, you need some more lessons.

No, you need better tyres.

[Deleted User]

Cheapest part worns and jobs a good'n :money:

Joe_Horner

nobbysn*ts wrote: »

Boring driving?

No, just smooth.

Vid here of Mark Higgins' lap of the TT circuit including telemetry:

http://www.youtube.com/watch?v=t7gmbQ8KxM4#t=193

Watch the G meter, it rarely goes above about 0.9g , even when he's braking hard or cornering like an absolute loon because all the transitions are progressive rather than heavy handed / footed.

Even ditchfinders will give 0.9g grip on a reasonable road.



eta: And no, I don't claim to be anywhere close to his league. But the same principle applies - grip is lost far more often by harsh control inputs than out-and-out cornering / braking forces..

nobbysn*ts

Joe_Horner wrote: »

No, just smooth.

Vid here of Mark Higgins' lap of the TT circuit including telemetry:

http://www.youtube.com/watch?v=t7gmbQ8KxM4#t=193

Watch the G meter, it rarely goes above about 0.9g , even when he's braking hard or cornering like an absolute loon because all the transitions are progressive rather than heavy handed / footed.

Even ditchfinders will give 0.9g grip on a reasonable road.



eta: And no, I don't claim to be anywhere close to his league. But the same principle applies - grip is lost far more often by harsh control inputs than out-and-out cornering / braking forces..

You do realise braking at 1g will stop you from 60mph in under 3s? Or accelerate to 60mph in the same time? Or pull a 9s quarter mile? If you think that isn't 'heavy handed', what do you think is normal driving? edit - your sure you want to do that on ditchfinders? And if you look, the meter only goes to 1g, so again, 0.9g is fairly excessive, not exactly smooth.

AdrianC

Joe_Horner wrote: »

Even ditchfinders will give 0.9g grip on a reasonable road.

<raises eyebrow> You reckon?

Joe_Horner

nobbysn*ts wrote: »

You do realise braking at 1g will stop you from 60mph in under 3s? Or accelerate to 60mph in the same time? Or pull a 9s quarter mile? If you think that isn't 'heavy handed', what do you think is normal driving? edit - your sure you want to do that on ditchfinders? And if you look, the meter only goes to 1g, so again, 0.9g is fairly excessive, not exactly smooth.

Yes, the meter only goes to 1g because that's pretty well the limit that physics will allow.

I have ditchfinders on the front of my Pug, with old "decent" tyres on the rear. I also have a Tapley meter which I picked up for checking the Dafs.

Even with the ditchfinders I can pull 0.95g braking on dry tarmac. Or I can jam the brakes on and lock the wheels, in which case the meter will show that they let go at around 0.7g (it holds the peak reading). The difference is in how they're applied, not how hard they're applied.

Smoothness isn't about not pulling high g - you can drive perfectly smoothly at speed. It's about not loading the forces up too quickly. If you jab a pedal or jerk a steering wheel the tyres will let go long before they will if you apply the control progressively.