Discussion
Sorry for another tyre thread 
also for posting in here but thought it relevent to Griff & Chim
What size R888 are you running?
Reason i ask is that i will (soon hopefully) have the luxury of two sets of wheels, 16" front & rear, also a 15"/16" combination.
Options being (i think)
15"/16"
F 215 50 ZR15 88W & R 225 45ZR16 89W (keeping a narrower front)
F 225 50 ZR15 91W & R 225 45ZR16 89W
16"/16" Looks like 225 45ZR16 89W only option.
Should i have the 15 or 16 front shod with the super sticky's or normal road tyres. Would it be better keeping the narrower front tyre for balance?
Andy/Guig's/Trackcar 
also for posting in here but thought it relevent to Griff & Chim
What size R888 are you running?
Reason i ask is that i will (soon hopefully) have the luxury of two sets of wheels, 16" front & rear, also a 15"/16" combination.
Options being (i think)
15"/16"
F 215 50 ZR15 88W & R 225 45ZR16 89W (keeping a narrower front)
F 225 50 ZR15 91W & R 225 45ZR16 89W
16"/16" Looks like 225 45ZR16 89W only option.
Should i have the 15 or 16 front shod with the super sticky's or normal road tyres. Would it be better keeping the narrower front tyre for balance?
Andy/Guig's/Trackcar Edited by Seasider coz i forgot Steve on Sunday 30th July 11:42
on Sunday 30th July 11:42 Edited by Seasider on Sunday 30th July 11:43
IMO i'd be reluctant to go smaller on front tyres than rear if you're going up on "stickyness" of tyre .. if the experince of my S and our race Tasmin are anything to go by they get *more* understeery the more grip you put through the chassis, I have 225 all round on the S (dunlop formula R) and the car is a slight understeerer on track, just at much higher speeds than on road rubber obviously. On road rubber it's a slight oversteerer (we're talking inherent chassis balance here, not any throttle induced atitude changes).
We noticed the same trend in the racer going from Kuhmo to Formula R to Slicks .. each time we've had to address an increasing understeer issue as the tyres go up in grip levels.
We noticed the same trend in the racer going from Kuhmo to Formula R to Slicks .. each time we've had to address an increasing understeer issue as the tyres go up in grip levels.
I'd have the 16s for R888s on track and the 15/16 combination for standard road use/tyres. Insurance is not affected either.
R888s work well in dry/wet conditions...they HATE standing water. turn into hydrofoils
But, in fact thats what I do!
the R888s are still only available in 16s, and that'll give you a world of grip. the increased grip levels over-coming the lack of set up for sometime.
The car then needs to be set on the 16s as the changed rolling cicumferences will lift the front reducing grip and inducing understeer AND lower the back aggrovating it. this will only be noticed when you're used to them!
the 15/16 combination and its altered set up, will not be noticeable in normal road use, however it WILL be noticed on track if you have the set up changed but run the standard wheels/tyres...Tiff Needell time
andy
tvrmonster
clear as MUD huh!
R888s work well in dry/wet conditions...they HATE standing water. turn into hydrofoils
But, in fact thats what I do!
the R888s are still only available in 16s, and that'll give you a world of grip. the increased grip levels over-coming the lack of set up for sometime.
The car then needs to be set on the 16s as the changed rolling cicumferences will lift the front reducing grip and inducing understeer AND lower the back aggrovating it. this will only be noticed when you're used to them!
the 15/16 combination and its altered set up, will not be noticeable in normal road use, however it WILL be noticed on track if you have the set up changed but run the standard wheels/tyres...Tiff Needell time
andy
tvrmonster
clear as MUD huh!
Guillotine said:
andy
tvrmonster
clear as MUD huh!
Errr no
Does the 50 profile dropping to 45 not keep the rolling circumference similar?
Edited coz just looked/rough measure about 3/4" diff in diam but thats on a 245 rear & 225 front. (Not sure if the wider tyre affect a ratio for profile at all
) + Toyo's site shows 225 50ZR15 91W
Dont know if available yi8tvr said:
Derek, May i ask why you want 888's on the grif, unless you going to do track days surely F1's are a better all rounder.
Them 888's are tiptoe tyres in the wet and need to be hot.
Just a thought
Mark
Them 888's are tiptoe tyres in the wet and need to be hot.
Just a thought
Mark
I hope to do a some more track also have trolley jack will change wheels
Although Andy's 15/16 profile v.s. set up change has worried me a bit. Also mine do tend to get warm
Edited by Seasider on Sunday 30th July 12:13
Guillotine said:
the 45/50 bit is a ratio to tyre width, so 50 on a 225 is smaller than a 50 on a 245 for the same rim size.
So ball now back in your court
225/50/15 & 225/45/16 So how different will these be
Will the difference be marginal ? When it comes to putting the roadies back on ? Seasider said:
Guillotine said:
the 45/50 bit is a ratio to tyre width, so 50 on a 225 is smaller than a 50 on a 245 for the same rim size.
So ball now back in your court
225/50/15 & 225/45/16 So how different will these be
Will the difference be marginal ? When it comes to putting the roadies back on ? The difference Derek is 14mm.
225/50/15 = 493mm
225/45/16 = 507mm
That of course is just a random guess. Im sure Randy Ace will confirm it
Seasider said:
yi8tvr said:
225/50/15 = 493mm
225/45/16 = 507mm
That of course is just a random guess. Im sure Randy Ace will confirm it
That is unless my calc's are wrong!! which they could well be
Agree on about 1/2" to 3/4" though
Oppps 493mm plus the other side 112mm = 605mm. 507mm plus the other side 101mm = 608mm
Howz about that then..
I only allowed for tyres one side
looks like a 3mm difference
Now ive helped you derek wrongly but still helped you can help me. What is the alternator on a sp6 off of ?????
And dont say an Hillman Imp
Edited by yi8tvr on Sunday 30th July 18:57
Edited by yi8tvr on Sunday 30th July 19:00
Edited by yi8tvr on Sunday 30th July 19:02
Guillotine said:
Ohh yes I was...and Mike Caine too! with nowhere to hide with just me, mike and the TMS challenge griff
happy days!
andy
monster
happy days!
andy
monster
I had a session booked Mr Caine
unfortunatly that didn't happen... So as you know i was lucky enough to have Steve drive me round
Don't remember anything going past Anyway lets stop hijacking the thread...
Sorry forgot it's mine anyway
so B
r off and stop telling me how quick your car is I have R888s on my Griff 500:
Front - 215/50 ZR15
Rear - 225/50 ZR16
Note the rears can be 50 aspect ratio – you do not need to go down to 45.
I have found the handling balance (under/oversteer) fine in damp/dry/hot. Also remember the original Griff 500 tyres (PAS option) were 215/55 front and 235/50 rear (later changed to 225/50 front and 245/45 rear). They have always had far more tyre on the back than the front (non-PAS originals were 205fr/235rr) so reducing that difference by fitting 215 fr/225 rr sticky tyres fits in with what trackcar is saying but from my experience you don’t need to go as far as having the same width tyre front and back.
You may/will need to increase the neg camber as they stick more and put your suspension under more pressure. I have stiffer springs too.
Those sizes fit the rims well and overall give a really nice feel. It certainly goes well!
Front - 215/50 ZR15
Rear - 225/50 ZR16
Note the rears can be 50 aspect ratio – you do not need to go down to 45.
I have found the handling balance (under/oversteer) fine in damp/dry/hot. Also remember the original Griff 500 tyres (PAS option) were 215/55 front and 235/50 rear (later changed to 225/50 front and 245/45 rear). They have always had far more tyre on the back than the front (non-PAS originals were 205fr/235rr) so reducing that difference by fitting 215 fr/225 rr sticky tyres fits in with what trackcar is saying but from my experience you don’t need to go as far as having the same width tyre front and back.
You may/will need to increase the neg camber as they stick more and put your suspension under more pressure. I have stiffer springs too.
Those sizes fit the rims well and overall give a really nice feel. It certainly goes well!
Can't help with the tyres but the following may help.
If you are looking for improved grip levels aero mods are probably the area you need to look at first. At the front of the car the tyres create 20% of the total drag so making them wider will make this even worse and can cause front end lift.
At the rear the curved boot shape doesn't help as it very nicely sends the air down the back of the car and underneath which at high speeds can make the rear unstable (Hence why the sagaris has its lip on the back).
If you are looking for improved grip levels aero mods are probably the area you need to look at first. At the front of the car the tyres create 20% of the total drag so making them wider will make this even worse and can cause front end lift.
At the rear the curved boot shape doesn't help as it very nicely sends the air down the back of the car and underneath which at high speeds can make the rear unstable (Hence why the sagaris has its lip on the back).
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