Steering weight and feel

[Keeper of The Kitten]

(and it was the offset I was referring to - greater distance between those two points will increase the self-aligning torque)

[S2central.net]

So wider track with wider contact patch should be a good thing then ?

Only downside being maybe some increase in bump sensitivity thru the steering ?

[Keeper of The Kitten]

Wider rubber is not necessary for increasing that offset value - and given enough camber that contact patch can be moved anyway!

[S2central.net]

I'm as confused as ever then... well almost...

I am definitely running with wheel centres 2x4mm further outboard than factory... Due to offset change.
I am definitely running 20mm wider contact patch on the tyres.
My track is definitely wider as a result.

[Rusty]

I noticed that on the track rubber going round a roundabout quite hard the steering really weighted up a lot. Must have been working hard!

[s2driveruk]

[s2driveruk]

I'm as confused as ever then... well almost...

I am definitely running with wheel centres 2x4mm further outboard than factory... Due to offset change.
I am definitely running 20mm wider contact patch on the tyres.
My track is definitely wider as a result.

Yeah thats my thought, running an 8x8j with ET30, i'm expecitng my track would be 14mm wider than stock

[S2central.net]

Your wheel centres are 14mm further apart, but your track is even wider if you have fatter rubber. 225 rubber is nominally 20mm wider than stock, so add 10mm track each side for half the wheel width... Thats a track width of 14+20mm bigger than stock - you are 6mm wider than me by nature of your smaller +ve offset.

[s2driveruk]

yeah makes sense and yep running 225/40/18 as you are...definately feels planted on the road, even more so with my track tyres and they are only an ET35 with 225/45/17

[Keeper of The Kitten]

Depends on what you think of as "track" ...the original definition is largely based on the centreline of the wheel, not the outside width ...but there is contention as to where even that centreline is to be measured, whether it is at the hub centre or the contact point (I prefer contact point).

Regardless of all that, the increased overall width brought about by wider rubber, combined with more offset, does increase the outer extremity of the tyre contact width - which in itself is bound to be of benefit to the lateral acceleration the car can achieve, with all other factors being equal.

The whole issue of what is in contact with the ground is a moving feast anyway, as the tyre pushes into the road on the loaded outer wheel in cornering, and the geometry inevitably moves as well as the tyre compressing ....things change!

[Keeper of The Kitten]

With lots of camber, remember, that the tyre lifts at the outer edge - so that effectively makes the width between the outer extremes of the contact patches smaller than if the same tyres at the same pressure were used with less camber. In harder cornering the contact patch will surely start to move outwards as more of the rubber meets the road.

In motorsport applications, it would be fair to say that maximum use of the tyre would be the most beneficial way - equal temperature across the width of the tyre. BUT that is only true if the tyre is able to come up to operating temperature. If it cannot achieve that, it is better to use less of the rubber (eg more camber) and get a smaller portion of the tyre working at the correct temperature.

[stiglet]

Yeah you got it about right.

here

Picture is a thousand etc etc...Wider wheels don't change the scrub radius, just different offset.

Edit: sorry that pic is kinda huge!

[Keeper of The Kitten]

lol I didn't do 14 years of slog in m-sport for no reason!

[stiglet]

With lots of camber, remember, that the tyre lifts at the outer edge - so that effectively makes the width between the outer extremes of the contact patches smaller than if the same tyres at the same pressure were used with less camber. In harder cornering the contact patch will surely start to move outwards as more of the rubber meets the road.

In motorsport applications, it would be fair to say that maximum use of the tyre would be the most beneficial way - equal temperature across the width of the tyre. BUT that is only true if the tyre is able to come up to operating temperature. If it cannot achieve that, it is better to use less of the rubber (eg more camber) and get a smaller portion of the tyre working at the correct temperature.

The coupe has next to no camber compensation Keeper, so I think you can safely assume the camber is always positive on hard cornering

[stiglet]

lol I didn't do 14 years of slog in m-sport for no reason!

No I was talking to Paul, you posted before me.