low profile tyres (ford kuga)

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The significant factor here is the aspect ratio:

Chris

probably.

Nope. 4 times nothing is the same as 2 times nothing.

Wide, low-profile tyres are usually peformance-biased, and summer compounds, so usually shit in snow.

Fashion.

Really hate this trend for silly big wheels and thin tyres.

I ended up downgrading the spec. of my 1-series from M-Sport to Sport just to get sensible sized wheels.

19" ultra-low profiles on a Kuga make absolutely no sense at all - mind you, the Kuga makes sod all sense, really.

Have you considered a Dacia Duster? - they are everywhere on mainland Europe, yet the Kuga is rarely seen, which kind of tells a story.

Not at all.

4wd, with the wrong tyres for the conditions, just means more tyres spinning. Or exactly the same number locked whilst braking or simply sliding sideways off the road.

It's the rubber compound and tread pattern.

It is. Lower sidewall, so less flex and compliance to absorb bumps.

Because they look cool, innit?

Since the tyre wall is shorter, the ultra low profile tyres needs higher pressure to stay afloat. That ineviatbly makes the wheels harder and you will feel the bumps in the road. Another problem is that insurers consider it as a modification and will charge higher premium.

If low-profile tyres are performance biased, then why are they not used in Formula 1?

Aside from the rules stipulating 13" wheels of a specified width, the sidewalls are part of the suspension / chassis design of an F1 car - they're a completely different proposition to a road tyre.

On Fri, 20 Sep 2013 20:01:07 +0100, johannes wrote= :

Why?

Some insurers will charge you for changing back to the larger profiles.

On Fri, 20 Sep 2013 20:23:38 +0100, johannes wrote= :

Because they're not allowed. Along with turbochargers, active suspension= =

etc.

The regulations mandate both the wheel size and the tyre diameter so the sidewall height is fixed by the difference. You can damn sure that if this wasn't the case the cars would run much lower profile tyres and put the suspension control back where it belongs, in the suspension, and not have half of it in the undamped and pretty much uncontrollable tyre widewall.

Nonsense. The suggested tyre pressures for the Ford Focus range stay pretty much the same all the way from 175/70/14s on base models all the way up to

225/40/18s on the Focus ST. The tyre pressure is designed to generate a given sized contact patch for a given vehicle mass on each corner and that's more or less independant of tyre profile or width.

The stiffer ride from low profile tyres is purely down to the reduced compliance in the smaller sidewalls which don't absorb bumps as well and pass more of the shock into the suspension. This could obviously be catered for with softer springs and dampers but that kind of obviates the point of the low profile tyres in the first place.

f1 suspension is nearly solid, just watch cockpit views to see the wheels (not) move up and down. Yet they are not allowed to make them solid (which would reduce weight and increase performance)

Quite so, you can see that they are different. But why? It is not enough to say they are different because they are different. There must be another explanation? I would imagine that F1 wouldn't compromise on tyre ability with the g-forces you get in F1. The tyres are also part of the suspension in a normal road car.

"rules"

The rules would be changed if every team wanted to use low profile tyres. The rules would only exclude them if they were unsafe. In other motors sports low profile do not seem the tyre of choice.