Friday night topic - most power through most narrow tyres

[drewpasmith]

Probably a bit meaningless without a formula to weight the figures across cars, but:

'92 Mercedes 600 SEL: 408 Bhp/428 ft·lb through 235/60/16s

[sparkyhx]

not standard, but my tuned 200sx was running 280ish thru 205's, then 320ish thru 225's

Thats 1.37bhp/mm followed by 1.42bhp/mm

[j_s14a]

|I'm struggling to find the tyre dimensions, but the 1967 Corvette Stingray must be a contender. These were rumored to be running about 560hp. I know the rear wheels are 7.5" wide, so conceivably it could be a 205 or 215?

[delta0]

gweaver said:

This might be true, up to the point at which the rubber starts to tear or vaporise.

Yes you will wear through the tyres quicker.

[iloveboost]

delta0 said:

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

Rotational forces (tractive forces) in either direction benefit from wider tyres. Reason is wider tyres run cooler than narrower tyres, so you can use a softer tyre compound and increase grip overall that way. Also the contact patch distorts less, as it's shorter and wider than a narrower tyre.
Here's an article on it:
http://www.autozine.org/technical_school/handling/...
Autozine is a website I used to read a lot. I make silly mistakes sometimes on here, but I learned a lot from that site.
Index for 'technical school' that has a lot of really useful geeky stuff on it (and it all seems accurate):
http://www.autozine.org/technical_school/tech_inde...

[Nigel_O]

up to 480-ish bhp through the front wheels, on 215 section Toyos, which aren't as good as the Contis that were fitted previously

Will easily will happily put down all the power from 2nd gear onwards in the dry. Slightly different story in the wet....

[Caddyshack]

My pug 205 cossie puts 468 bhp and 500ftlb of torque through 195/45s when in 2wd mode on the skyline box...well it doesn't very well, even with Supra rear diff on maxi weir kitted LSD, switch to 4wd and it does it easily as the centre diff locks and the front has a quaife atb....no worries then!

1100kilos. Road car, not racing car.

Edited by Caddyshack on Wednesday 5th August 21:30

VERY. Old pic from Aces before I owned it, this is still in max power mag cover trim....it is very subtle now

Edited by Caddyshack on Wednesday 5th August 21:31

[e46m3c]

How does 550bhp 255 fare?

[Caddyshack]

Better, recent, pic. The 468 bhp will be 530 with a better intercooler. This is chasing veyron power to weight on 195s

[Garett]

My Saab 9000 had 240 bhp and 266 lb/ft pumped through its 195/65/15 shod front tyres. That could get a bit wayward if you weren't careful. No fancy diffs or electronic aids, just a hulking great thwack of turbocharged Swedish muscle, I loved that car!

[mato]

Steven_RW said:

I have a 2007 Mini Cooper S that ran 265bhp to 270bhp and 280lb/ft through 205 section tyres.

We broke a piston skirt and now have CP forged lower comp pistons and Carillo forged rods sitting ready as we rebuild the engine, including closing the deck so we can run it up and then add something like a T88 turbo in a compound setup under the boot floor.

It should be running quite a few bhp by then. No plan to change the tyres at this stage.

Cheers

RW

Hi, do you have a build thread for this?
Thanks

[Boshly]

Rob.043 said:

Plenty of wild numbers for modified cars, my stock E39 540 has 225 section tyres all round, and 286bhp.

225mm x2 tyres / 286bhp = 1.57mm per HP.

littleredrooster said:

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?

I've already posted but my Challenger Hellcat is stock, current and factory fresh and puts out 707bhp through 275's.

2.57bhp/mm or 0.34mm/bhp whichever way you want to quote it.

Winner winner chicken dinner - or is it???

[Neil E 99]

James P said:

Would win the opposite competition I think. I recall LJKS writing that the 2CV was the most generously tyred car per horsepower based on (if memory serves) 29bhp and 125 section tyres. I'll get my coat ...

I never thought of that James.
I think I had beter get my coat........http://www.pistonheads.com/gassing/imgs/9.gif

[saaby93]

Looking for new tyres, Michelin Alpin came up
http://www.tyrereviews.co.uk/Tyre/Michelin/Alpin-A...

Ok I'm not looking for Alpin tyres but it's noticeable that for a given spec of tyre that due to their curved profile they have a lower contact point than normal.
Lower contact point = greater pressure per square cm = greater grip? ala 2CV in a ploughed field

[Peanut Gallery]

Not stock, and not narrow, more a curiosity:

Those drag racing rail cars - Top Fuel in wiki:
10,000 is a given upper limit of hp,
47cm wide tyres, so 940mm width total,

This to my maths is 10.6hp/mm or 0.094mm/hp, whichever way you want to quote it.

Using 7000hp brings this down to 7.45hp/mm or 0.134mm/hp

Sources-
http://www.santapod.co.uk/dr_anat_topfuel.php
https://en.wikipedia.org/wiki/Top_Fuel

[hornetrider]

My 550i has 370ish bhp through standard 245/40/18. I believe you can also get a 550i SE with 17s which run a 225/50.

[PHMatt]

Cytokine said:

PHMatt said:

I was foolish enough to fit 205/35/18's to my MR2 Turbo that was tuned to about 320bhp at the time.
When I drive it sideways up a kerb, over a verge and into a fence I replaced those with 225's on the back.

It was annoying as the car really did need staggered wheels and tyres but there's not too many manufacturers out there that make wheels in different widths. I ended up having staggered tyres on the same width wheels (didnt come with OEM Wheels before anyone says it, they were gone long before I bought it)

I had 225's on the front of mine and 245's on the back and that was only an NA. Never went sideways unless you wanted to to like that. Could corner at amazing speeds without any fear.

Try one with 320bhp on 205 Nankangs in the wet.

[PHMatt]

Du1point8 said:

maybe this?

The wheels aren't driven - it's pushed along by thrust.

[900T-R]

IIRC the Marcos TSO was shod with 225/40/18 all round in a bit to keep things nice and progressive, with the optional performance pack on the LS2 engine, quoted power was something like 465 bhp. Wasn't exactly lacking in the grip department according to Evo's road test report, either...

[Boshly]

swerni said:

2 drives wheels not 1

Still win by a good margin .

Not until the LSD cuts in

Ok fair enough