Tyre & wheel characteristics

[hertsbiker]

hi, can someone settle the argument about what's the grippiest setup;-

big wheels, low profile tyres, or smaller wheels, higher profile


Before you reply, consider;-
a) F1 cars with titchy wheels + high profile tyres

b) Touring cars with tyres like elastic bands round cotton reels.


'cos I can't work it out !!! hope one of you lot can.

ALSO ! if I have a high degree of wheel camber, does going even lower profile cause any problems?


cheers, Carl

[adrianr]

The "grippiest" set-up is the one that puts most rubber on the ground for the most time. Generally this is down to diameter and width of overall combo, not the wheel size and tyre profile. However in the real world it is factors such as bumps or road camber that make most difference as these limit how much of the theoretical max grip is available at any time.

I don't think motorsport is that good a guide sometimes - most F1 rules are now to slow the cars down, and touring car teams might be tempted to put huge tyres on so they can sell them to boy racers!

Generally tyre profile is a trade off between ride comfort (better with high profile tyres) and tyre stability (better with low profile).

The wider and squarer your tyre is, the more important it is to have it perpendicular to the road and therefore the more attention you have to pay to camber control. Vintage racers run 19" wheels, but with round section 6-8" tyres (like your bike?) so camber is more-or-less irrelevant to them.

AdrianR

Edited by adrianr on Thursday 6th December 17:23

[kevinday]

Another point with FI is that the tyre also provides some of the suspension action

[MikeE]

I don't know about absolute corning grip but I do know (from a little research with my Tuscan and a mates) that my low profile tyres (18" wheels) are much easier to light up than the higher profile (16" wheels) I guess this is down to the ability of the tyre to absorb some of the initial force when you side step the clutch?

[hertsbiker]

interesting points made here..

So the big wheel thing may actually be just a marketing ploy?

I was only wondering 'cos my mates BM has 19 inch wheels, and handles very well - but that has a problem getting power down, just as you said.

Also the lower pro the tyre, the less well it seems to work on snow !

cheers lads.

[350matt]

This is a good point as the chassis engineers I know run reasonably large sidewalls on their own cars. I myself also prefer a 'tall' tyre as it tends to give more feedback as you approach the limit of adhesion as well as improving traction, as the tyre can comply to the road surface better and so keep the surface area in contact with the road more constant. Also tall tyres give a much better ride, the advantage to a low profile tyre is mainly in steering feedback as the steering torque doesn't have to wind up as much tyre to start transmitting laod and therefore feel. And of course they look better which is the main reason they're fitted but who said fashion had to make sense?
The F1 tyre is like that as the rules call for a 13" rim however the construction of the tyre is completley different to a normal road tyre as they are mosty carbon fibre shells and the tyre sidewalls are extremly stiff and allow for very little movement.
Basically it boils down to how good and even your road surfce is. If you are going to use the car on smooth race track, then its a stiff sidewall /low profile. If you use the car on real roads (ie bumpy as hell) run a sensible tyre wall size.

Matt

Edited by 350matt on Saturday 8th December 16:13

[Hazzer]

Err None of the above,

There is no magic formula for which setup provides the most grip - the whole shebang depends on the vehicle, eg size, weight, balance, tyre type construction, material to name but a few.

The whole grip thing depends on the slip angle (management of) the tyre
- This is a non linear scale, oftern used by chassis engineers to work out when the "grip" will run out..

I really should get out more....!

Haz