Tyre Heights/width For 1/4 Mile

[TOYR33]

hi guys,

just wondering would there be an advantage of using a tyre with a bigger wall e.g (60) for less wheel spin of the line?

for e.g i used my 17/45/235 rims (potenza gIII) last time for the 1/4 mile and it was getting heaps of wheel spin (b/button clutch) if i used a 16/60/215 but flattend to say 16-18psi would it grip more as the tyre has more flex on the wall?

[scathing]

Think about it logically for a second. Why does increased sidewall flex give more grip?

The deformation of the sidewall then increases the effective surface area because the tyre squashes and spreads.

But if you're going with a tyre that has less contact patch, then all you're doing is getting it to a point where the contact patch was the same size as the less flexy but wider tyre.

Obviously the final word will depend on the specific application and would require testing, but logically all I can see happening is you having the same amount of grip.

If you were going to a 235/60 R16 tyre from a 235/45 R17 I'd say yes, but since your "new" tyre choice is narrower I'd say it was pretty line ball (assuming your tyre is the same make and model).

[TOYR33]

thanks, ye that sounds right, just had a few ppl tell me dont bother with rims (something like a 45 profile) as it will only spin especially with a b/bustton clutch, i will be testing both sets of tyres this saturday so wel see what happends,

has anybody had any Actual experiences were they have compared a both smaller and larger profiles?

[Fabio]

The bigger the diameter, the harder it is to spin. The wider the tyre, the more grip. The bigger the profile, the more it will absorb the shock from take off. The lower the pressure, the more it will absorb the shock from take off, and increase contact patch. This is all assuming all other this are equal. Also big burnouts are bad for street tyres, but good for race tyres, if using street tyres, try driving around the water box and just spin the tyres enough to make sure they are clean ie no stones etc.

[2rismo]

  Quote

Think about it logically for a second. Why does increased sidewall flex give more grip?

The deformation of the sidewall then increases the effective surface area because the tyre squashes and spreads.

Wrong. By your logic, Top Fuel cars would be using 60" wide slicks with 40mm of sidwall and running the times they are - or better!?!?!?

Think about it logically for a second.

Adrian

[TOYR33]

ye that right,

so im assuming the 16/215/60 will work betta say at 18-20psi than the 17/235/45?

i think the main problem is the clutch coz it so frictiony and its pretty much impossible to ride and from the take of shock/stress on the small profile just starts spining. the car makes just over 200rwk.

any ideas on a better take of strategy

the 17's are potenza gIII's, and the 16's are good year eagle ga

[mazgtr]

The width of the tyre also makes a big difference, people often state that to increase grip you should fit a wider tyre, but thats not always true, your cars weight is simply spread over more surface area of tyre with a wider choice, a narrower tyre can actually provide more stability.

Matching your cars gearing to the your tyres diameter is also very important. Genrally the samller the diameter wheel/tyre the better the acceleration, but lower the top speed.

Tyre pressures also effect the cars grip, as does the friction co-efficient of the tyres rubber, the weight on each tyre and the force applied to them.

[evil_weevil]

Mate,

as a guide - I have dunlop 3000R's on my 33gtst - just a normal road tyre basically!

225/60/16

I dropped the pressure down to 22psi and was doing 1.9 60 footers at WSID (stock clutch) with a gay effort burnout haha

that might help you in theory

Edited June 21, 2006 by evil_weevil

[TOYR33]

  evil_weevil said:

Mate,

as a guide - I have dunlop 3000R's on my 33gtst - just a normal road tyre basically!

225/60/16

I dropped the pressure down to 22psi and was doing 1.9 60 footers at WSID (stock clutch) with a gay effort burnout haha

that might help you in theory

thats a pretty mad 60'' time man, ye standard clutch is much better than b/button as theres no ride in the clutch its on or off, so wen u try take off at 3-4000rpm ~~~~~

what was your finanal 1/4 mile time with a your 60' at 1.9 and mph?

[evil_weevil]

Yeah I was launching at 4-5k

hahah 14.5 @ 95mph

thats just a pod and cat back, if I change gears faster and more brutal - maybe 14.4 in it?

[Thunderbolt]

Usually fitting the widest possible tyre to the rim will give you good traction. You know how some people stretch 225s over 9" rims. Well you want to do the opposite basically. The sidewalls will flex more and the contact patch will be better to begin with too.

This is probably the reason why evil_weevil was getting good 60 foots, because of the fact that 225s are wide for a 6.5" rim.

[evil_weevil]

  Thunderbolt said:

This is probably the reason why evil_weevil was getting good 60 foots, because of the fact that 225s are wide for a 6.5" rim.

no....I thought it was because I'm such a skillful driver?? hehehehe jokes

Some people thought I was running semi's because of the 1.9's.

[benm]

Launching is an art - their is more to it then how wide your tyres are or what brand of rubber they are.

Track prep, track temperature, clutch type, tyre compound, tyre pressure, horsepower, rpm etc all influence your launch.

On a side note I have a pair of unused 300ZX rims with very very warn Nitto NT555R rubber (255's) sitting in my garage if someone wants to throw some mulla my way

[2rismo]

1.9 second 60' times are about right for shitty street rubber and a good launch on them. IMHO, semi's do SFA better than street tyres at the drags.

Adrian

[2rismo]

  benm said:

Launching is an art - their is more to it then how wide your tyres are or what brand of rubber they are.

Track prep, track temperature, clutch type, tyre compound, tyre pressure, horsepower, rpm etc all influence your launch.

On a side note I have a pair of unused 300ZX rims with very very warn Nitto NT555R rubber (255's) sitting in my garage if someone wants to throw some mulla my way

I can tell you that someone should use ben's tyres asap. Those tyres have gone 1.68 60' before Awesome

[TOYR33]

  2rismo said:

I can tell you that someone should use ben's tyres asap. Those tyres have gone 1.68 60' before Awesome

i would take them, but i live in melb spuin an need them for saturday,

any special take off techneeks with brass button clutches? were u cant really ride? ive tried hand brake helps a little

[evil_weevil]

TOY - practice makes perfect?

keep practicing and you will soon find out the best way

Adrian - In the NSw times thread - most other people are doing 2.0 + 60footers, m impressed with my efforts

[2rismo]

  evil_weevil said:

TOY - practice makes perfect?

keep practicing and you will soon find out the best way

Adrian - In the NSw times thread - most other people are doing 2.0 + 60footers, m impressed with my efforts

Didn't mean it to sound like a knock, mate. Good work on the times! Just wanted to make the point that the 60' was about right for a more than capable driver on crappy tyres. More of a compliment when i thought it than when i re-read it.

Buy some better rubber champ - you wont know your car!

Adrian

[evil_weevil]

hahaha Oh I know you werent having a go mate, sorry if I came across like that !!

In my old VT LS1 my best was 2.3...hahah

Yep - Going to do some research with the tyre rating thread asap and get some good rubber !!

[TOYR33]

so, would you say taking of with the hand brake up sitting on boost as you launch or just ride the clutch as much as possible and take of on 0 psi, as for example autos when they stall it up they always take of on boost