Friday night topic - most power through most narrow tyres

[Google [bot]]

kambites said:

speedtwelve said:

Years ago when I had a Lancia Delta HF Turbo it was putting (as standard) 140bhp/140 lbft through factory-spec 165 section tyres. Even for the late 80s it was a tad undertyred...

Surely it was putting it through all four wheels though? That's cheating.

[Hamish Finn]

205/70/VR15 on a 7.2 litre Jensen Interceptor. Weighs two tons, and behaves perfectly acceptably, especially on Michelin classic XWX.

Narrow tyres?

[PhillipM]

delta0 said:

Technically area of contact has no effect on grip. Obviously cornering and particularly wear benefit from some width.

Your teacher lied to you. Sorry, they all do it.

I'm gonna go for anything group B on ice tyres...

[delta0]

PhillipM said:

Your teacher lied to you. Sorry, they all do it.

I'm gonna go for anything group B on ice tyres...

Ice is a little different. For the road then narrow or wide tyres the actual grip is the same. Max acceleration a = u g coefficient of friction of the tyre x gravity. If you want more then wings help a lot as they push down into the tyres.

Edited by delta0 on Friday 24th July 23:32

[PhillipM]

delta0 said:

Ice is a little different. For the road then narrow or wide tyres the actual grip is the same. Max acceleration a = u g coefficient of friction of the tyre x gravity. If you want more then wings help a lot as they push down into the tyres.

Afraid not, tyres are a viscoelastic system and they also have some chemical bonding going for them, mu is not a fixed constant irrespective of load anywhere outside of a perfect physics simulation, neither is the contact patch size constant given the respective stiffness of the sidewalls and loading.

[Talksteer]

TVR T350 with 4.3 - 420bhp, 235/r18 tyres. Not really an issue.

[delta0]

PhillipM said:

Afraid not, tyres are a viscoelastic system and they also have some chemical bonding going for them, mu is not a fixed constant irrespective of load anywhere outside of a perfect physics simulation, neither is the contact patch size constant given the respective stiffness of the sidewalls and loading.

u does change according to load and temperature definitely (and that can be modelled). That's why you get much higher u from racing slick tyres with a softer compound but when you do exceed the grip and they slip typically more than 5% then u falls dramatically. Road tyres are a little less of a cliff edge than that fortunately!

[Boshly]

707bhp through a pair of 275/40's

Must be the same as 450bhp through 165's (can't be bothered to work it out)

[Benni]

234mph in 5,9 sec on the quartermile.................on 10.5 tires :

http://www.yellowbullet.com/forum/showthread.php?t...

Amazing what can be achieved with those skinny rubbers.

[g3org3y]

BMW i8 would be a decent example.

356bhp through 195/50 R20 & 215/45 R20 as standard (options are 215/45 R20 & 245/45 R20)

[Google [bot]]

https://m.youtube.com/watch?v=QuC9E3H6FH8

[s m]

speedtwelve said:

Years ago when I had a Lancia Delta HF Turbo it was putting (as standard) 140bhp/140 lbft through factory-spec 165 section tyres. Even for the late 80s it was a tad undertyred...

Yes indeed, I remember them well - a friend had a few after he got fed up of fast Stradas - they used to literally 4 wheel drift in fast corners. The earlier ones had less power and slightly wider tyres

[wst]

Napier Railton - 564hp, 6 inch wide tyres. So.. 150 wide.

[otolith]

Must be something like the old racing cars mentioned.

285bhp;

[Puddenchucker]

1970s supercars had narrow tyres:

Lamborghini Countach LP400 - 375hp, 205/70 R14 rear tyres

Ferrari 512BB - 360hp 215/70 R15 rear tyres

Although it could be argued that the Lamborghini started the whole trend for wide tyres, as the later LP400S had Pirelli P7s at 345/45 R15

[jogger1976]

The 68' Dodge Charger R/T (Bullit car) runs something like 205/70/14 and puts out 400+ hp
The 365 GTB Daytona is something like 205/70/15 and the latter ones had around 400 bhp
Lancia Delta S4 205/55/16 and 550bhp

[DS197]

FunkyNige said:

300HP through one 190 tyre (most of which doesn't touch the ground)

What's it like to ride mate?

[apotts]

Surely: https://www.youtube.com/watch?v=SgN1387v4sA

[littleredrooster]

...and, as usual, most posters have missed the question.

Gandahar said:

...which man, or lady, drives a car with skinny tyres and large bhp through the driven wheels?

Is there anyone with more than 200 bhp with less than a 205 for instance?

I am sure there is. Show us your metal. Or rather lack of it.

Easy to go back 40-50-60 years and say "Ooo - look at those skinny tyres!" FFS they were all like that!

The topic is in the current tense - who drives a car with skinny tyres?

[kambites]

speedtwelve said:

kambites, the original HF Turbo I had was FWD only. Later came the 4WD HF Turbo and then finally the Integrale. I couldn't afford an Integrale

Well you learn something new every day. I didn't know there was a FWD HF Turbo.