PDA

View Full Version : wrc tyres



KnifeEdge_2K1
08-02-2004, 05:32 PM
anyone know what the wrc cars use on tarmac stages? gravel stages? (the ice/snow ones dont really matter since they get one's with spikes )

i heard the regulation maximum was 225 width and i thought that's kinda low

i'd expect the larger cars (impreza and lancer) to use something in the range of 245s on the tarmac stages

KnifeEdge_2K1
08-02-2004, 05:46 PM
neone know how many Gs wrc cars pull? i'm assuming it will be in the area of 1.2-1.3 gs

Matra et Alpine
08-03-2004, 03:16 AM
neone know how many Gs wrc cars pull? i'm assuming it will be in the area of 1.2-1.3 gs
Subaru has been measured at 1.8G lateral for tarmac event setup.

But that's only one aspect of the G-forces a driver feels. They hit MUCH higher shock loads when they use a snow bank to steer, hook a wheel in a ditch and hit the fastest yumps in Finland and Oz.

Matra et Alpine
08-03-2004, 04:19 AM
anyone know what the wrc cars use on tarmac stages? gravel stages? (the ice/snow ones dont really matter since they get one's with spikes )

i heard the regulation maximum was 225 width and i thought that's kinda low

i'd expect the larger cars (impreza and lancer) to use something in the range of 245s on the tarmac stages
FIA regs at www.fia.com - Appendix 5 of http://www.fia.com/resources/documents/302462293__FIA_Rally_Prescrip_2004_a.pdf

BUT, it's in tyre-design speak and determines max tyre tread patch size as 140x140mm, this translates to a 225 tyre :)

On 4WD bigger tyres aren't always better as the handling becomes nasty in the dry if too much grip.

Also, don't want wide tyres on gravel stages or loose tarmc. It takes a tyre to be able to BITE down into the stable stuff. Fat tyres just through lots of gravel on loose stuff like driving on marbles - BAD :)

The max I've seen were the A110 GrpIVs and MaxiTurbos which would run 10x15 rear rims and 305 tyres IIR

KnifeEdge_2K1
08-03-2004, 07:30 AM
Subaru has been measured at 1.8G lateral for tarmac event setup.

But that's only one aspect of the G-forces a driver feels. They hit MUCH higher shock loads when they use a snow bank to steer, hook a wheel in a ditch and hit the fastest yumps in Finland and Oz.

wow i was way off with my prediction of 1.2-1.3 gs

i guess rollcages add alot more rigidity than i thought

KnifeEdge_2K1
08-03-2004, 07:34 AM
BUT, it's in tyre-design speak and determines max tyre tread patch size as 140x140mm, this translates to a 225 tyre :)

On 4WD bigger tyres aren't always better as the handling becomes nasty in the dry if too much grip.

Also, don't want wide tyres on gravel stages or loose tarmc. It takes a tyre to be able to BITE down into the stable stuff. Fat tyres just through lots of gravel on loose stuff like driving on marbles - BAD :)



hmm, 225 tyres ... i'm still in awe of how they manage to pull 1.8gs with tyres that are smaller than stock ... oh well the tread design has a lot to do with it as you've said b4 and i guess the racing tyres arnt desgined to last thousands and thousands of miles like regular street tyres

newayz i'd just feel a lil better if they were running on 245s or at the very LEAST 235s but thats just my stupid macho ego bigger the better side of me speaking :P

Matra et Alpine
08-03-2004, 08:03 AM
newayz i'd just feel a lil better if they were running on 245s or at the very LEAST 235s but thats just my stupid macho ego bigger the better side of me speaking :P
Wouldn't want to go anywhere near a Scottish forest stage with fat tyres on :) never mind Argentina or Corsica or .....


But for tarmac events I'd like them to be able to go crazy again - even if just for the national rallies.

PS: The lateral G is more to do with the suspension rather than the chassis rigidity. Chapman proved that point way back in the 60s :)

KnifeEdge_2K1
08-03-2004, 12:10 PM
PS: The lateral G is more to do with the suspension rather than the chassis rigidity. Chapman proved that point way back in the 60s :)

hmm good point but wouldn't excesive body roll ruin a good suspension setup? :P another example of why not to put all ur eggs in one basket

megotmea7
08-03-2004, 11:37 PM
body roll and chassis rigidity aer 2 completly different things, body roll is how much the body leans in the oposite direction of he turn and is almost totaly controled by the suspention setup, chassis strength is how resistent o flex the chassis is in cornering and bumpy situations... :)