Brake Pedal Fail When Cornering - Australia

[Tinerfeño]

Soft sidewalls would allow the effective rolling diameter to change during hard cornering.

There are steel belts below the tread. How the lenght of these will change?
Sidewall flex changes will not affect the forward movement per tyre rotation.

 

[Skydance]

If I recall rightly, the automotive press reviewers of the new shape Jimny reported a similar issue when taking fast corners. Can't remember if Suzuki adjusted anything or it was just a case of it being that type of vehicle that needed early intervention?

Yes the Jimny does it with its soft rolly polly suspension on fast bends, going up or down hill with barriers in front. It applies the stability control/ABS and it’s quite scary when you don’t know.

Jimny during the testing phase disconnected the auto brake instead opted for the stability control instead.

The fix is to upgrade suspension (with less roll) and fit stronger sidewall AT tyres.

Another thing to mention here is (ADAS vehicles only). People who lift their vehicles, taller tyres, new windows fitted, winch fitted should ideally get their camera on the ADAS re calibrated (within a certain threshold). This is why sometimes it gives false alarms like this.

These are things I learned with the Jimny.

 

[255/85]

There are steel belts below the tread. How the lenght of these will change?
Sidewall flex changes will not affect the forward movement per tyre rotation.

I am under the assumption that, when a tire is under inflated, the steel belt will become slightly concave - bend upward toward the rim - and mirror the normal convex curvature of the tire to retain the length of the tread. The belt (circumference) has to go somewhere when the radius is reduced. We don't see the tread from the side. We see the bulging sidewall and think the tread is straight. I could be misinformed though or my logic flawed. It wouldn't be the first time.

 

[Tinerfeño]

This may happen if:

• The tyre pressure is very low.
• Tyre sidewalls are stiff (bias-ply tyre, radial tyres have softer sidewalls).
• The surface is soft and will allow side areas push into the surface.

With radial tyres on a flat hard surface I really don't believe this will happen. And remember that the weight on the tyre is still supported by the deflatet tyre, in case of en empty Grenadier it is ~675 kg/tyre (~1500 lbs/tyre) and this needs to go to the surface.

 

[NQ94]

This bloke put a Gopro in a car and SUV tyre to see what happens.

View: https://youtu.be/rILyBg7ZjeI?si=TZMbwkD4NotHe0Yc

View: https://youtu.be/UZQXPLfOPXc?si=yc_RuPMPDB68rOA9

 

[Tinerfeño]

Nothing strange on those. But good to see how the balance powder will spread inside a tyre.
And the pulsing of the tyre which we see s actually a bulge constantly rotating as car goes on.
Sidewall flexing is already significant. Much more when tyre is deflated.

And you really can't deflate the first tyre

 

[Pat]

It did happen to me several times but just in one hair needle turn going downwards (steering on the left side) - while braking the outer right front might slip and ABS is intervening - very soft brake pedal for 1 second. In the winter I can replicate it always in that specific turn below 5 degrees Celsius with the standard AT Bridgestone Dueler tires (in the first 10 km) - it does not happen with Michelin winter tyres wich are softer. So guessing a mix of tyre temperature, rubber component of AT tyres and and sensitive ABS intervention.