Stephen Read

Had a close look at a current Sauber F1 car today which was parked next to one of Mansell's 1992 Williams' at my local shopping mall (don't ask) and I was struck by the difference in rear tyre width comparing then with now.

However, the question I have though is why are are the wheels on the current car only 13" in diameter?

Here are the dimensions that were on the Sauber's tyres:

325/45/R13 Rears
265/55/R13 Fronts

I guess they are limited by the rules but to what end?

Does a smaller wheel rim give you the lowest possible unsprng mass and thus more grip?

I presume that the larger wheel sizes seen Touring Cars are due to the need to fitt big brakes but with F1 cars being much lighter and allowed to run Carbon disks, they don't need massive disk diameters to get the required braking performance....

If that was the case though you might expect to see smaller rims on the rear wheels as they don't need to cover a huge disc and lower unsprung weight would give better grip and thus traction!

I must be missing something......

ricco

This is something i've wanted to know for ages! I've sent an e-mail to the ITV studio thingy but never got a reply.

I'd also add that by using bigger wheels with low profile tyres allows you to control all travel via the suspension (more predictable/controlable), by using these high profile tyres surely can't garantee that the handling will be the same after a tyre change? After all diferent pressures etc will give different charcteristics!

Hope someone can give a decent explanation?!?! I seem to remember someone on here works for Jordan... are you out there?

Tone Loc

iTrader: (1)

An F1 car could not run 17" wheels and low profile tyres because of how stiff the suspension is. If they did the driver would probably break his back over the bumps!!!! The tyres act as part of the suspension, thats why the tyre pressures are so critical in F1.

Tony.

RichS

Pretty sure it's the rules, more than anything else, that dictates the wheel size.

Given the differences between the cars, from one team to the next and from one year to the next - it would seem unlikely that no team (in recent times) would never have experimented with a larger wheel if the rules allowed it.

Also, I would think that the ride control and handling of the car would be much easier to adust by altering the suspension rather than relying on tyre pressures to do this which will alter anyway depending on the tyre temperature.

Standing by to be corrected of course...

KenG

I was in the garage of one of the F1 teams at last years qualifying (Silverstone) and believe you me they are very sensitive about anyone knowing what tyre pressures they run. I could get a couple of years worth of tyres for the Scoob for the price of one of the tyre pressure gauges.

Various tings about the tyres were mentioned - volume of air when heated, heat dissapation, tyre wall flex and thickness of rubber. Some or all of which would preclude low profile tyres.

Ken

Tsbar

I suppose one possibility is that it is for maximum acceleration (smaller wheel = faster acceleration) considering they are always braking for turns and trying to pass, I would think acceleration would play a huge role (as well as every other reason posted so far!).

Ts (who admittedly knows nothing about F1)

Adam M

tsbar,

smaller wheels would give faster acceleration if the wheel was running on the road, but s3ince there is a tyre in the way, it is the outer radius of the tyre which affects things.

A low profile on a big rim or a high profile on a small rim give the same torque at the contact patch (assuming they have the same outer radius) and the same torque is transmitted by the driveshaft.

David_Wallis

Im sure they also use nitrogen in them as well...

David

rogerw

the fia rules 2001 concerning wheels and tyres as follows

article 12: wheels and tyres

12.1 location: wheels must be external to the bodywork in plan view, with the rear aerodynamic device removed

12.2 Number of wheels: The number of wheels is fixed at four.

12.3 wheel material: all wheels must be made from an homogeneous metallic material.

12.4 wheel dimensions:

12.4.1 Complete wheel width must lie between 305 and 355 mm when fitted to the front of the car and between 365 and 380 mm when fitted to the rear.

12.4.2 Complete wheel diameter must not exceed 660mm when fitted with dry-weather tyres or 670mm when fitted
with wet-weather tyres.

12.4.3 Complete wheel width and diameter will be measured at axle height when fitted with new tyres inflated to 1.4 bar

12.4.4 wheel nead diameter must lie between 328 and 332mm.

which means from 12.4.4 wheel diameter can be no larger
than 332mm (13 "). They would have a large a wheel as possible if the rules allowed and to hell with the drivers comfort.

Stephen Read

Thanks for that, rogerw!

(Just back from holiday)

carl

I can't believe the Sauber's rears are only 325mm across. That's about 13". I thought the 'narrow track' regs reduced the rear tyre width from 21" to 18".

mutant_matt

They do use Nitrogen instead of air as it is more consistant (apparently) as it heats up/cools down....

Matt