Never mind the quality...
Discussion
...tell me about the width. Rear tyres, that is.
I know wheel/tyre sizes seem to have been done to death, but I've trawled the vast depths of the PH forums, and can't find information on maximum rear wheel and tyre sizes.
I've currently got Goodyear Eagle 'road' (MSA list 1A) tyres on 17" wheels;
Front: 7x17 with 225/45
Rear: 8x17 with 245/40
I'm looking to get an additional set of wheels and fit them with soft, semi-slick type (MAS list 1B) tyres, just for sprints and hillclcimbs. The Goodyear's are great (IMHO better than the So2s they replaced) but must be too soft beacuse they've done nearly three seasons!
Is there anyone out there who has successfully fitted wider rears, either on 17" or 18" wheels?
FWIW, I can tell you that with my current front tyre set-up, the wheels just graze the arches on full lock and, as I remember it, Mike Catania's sprint Griff 500 had (I think) 18" rears which did occasionally catch on the wheel arches.
All help greatly appreciated.
I know wheel/tyre sizes seem to have been done to death, but I've trawled the vast depths of the PH forums, and can't find information on maximum rear wheel and tyre sizes.
I've currently got Goodyear Eagle 'road' (MSA list 1A) tyres on 17" wheels;
Front: 7x17 with 225/45
Rear: 8x17 with 245/40
I'm looking to get an additional set of wheels and fit them with soft, semi-slick type (MAS list 1B) tyres, just for sprints and hillclcimbs. The Goodyear's are great (IMHO better than the So2s they replaced) but must be too soft beacuse they've done nearly three seasons!
Is there anyone out there who has successfully fitted wider rears, either on 17" or 18" wheels?
FWIW, I can tell you that with my current front tyre set-up, the wheels just graze the arches on full lock and, as I remember it, Mike Catania's sprint Griff 500 had (I think) 18" rears which did occasionally catch on the wheel arches.
All help greatly appreciated.
Don't you mean too hard if they have lasted longer than you thought? 
richb said:
Digga said:
Is there anyone out there who has successfully fitted wider rears, either on 17" or 18" wheels?
Yeah, I've got 255/35x18 Bridgestone SO2's on 18x8 RL7 rims, what do you want to know? Rich... Do these clear the wheelarches OK then? And d'you reckon I'd squeeze an 8.5x17 on there?
Yeah, no problems - I'm running 40mm off-sets and lowered Nitron dampers. Can't say about the 17" but it's the rubber that will touch not the rim so it's more the width of the tyre you want to be asking about - but for what it's worth I would recklon so because my 8" rims are better suited to 245 so a 255 on an 8.5" rim should work.
Edited by richb on Tuesday 16th January 18:58
Rich,
Thanks for elaborating. Yes I did wonder if that 255 tyre width would be better with an 8.5.
Rim size to tyre size reccomendations seem to vary between tyre types/manufacturers and I was thinking that my 245s would perhaps also sit better on 8.5s.
In my search through past PH tyre thread, I know GreenV8S has posted on a few occasions in regard to the fact that (for track/sprint use) it's better not to 'over-tyre' the rims. Although, as someone else pointed out, the dynamics of the V8S rear swing-arm suspension vs. the Griff wishbone set-up may mean certain aspects of comparison are redundant.
Given that, on 17" wheels at least, a 225/45 seems to be the widest sensible choice, and for the benefit of anyone else pondering this at the moment (or trawling PH in future), these are the likely 'list 1B' suspects for 17" rear wheels at this time:
Manufacturer - rim size* for; 235/40; 245/40; 255/40
Toyo R888 - 8.0 to 9.0; n/a; 8.5 to 10
Kumho V70A - 8.5; 8.5; n/a
Yokohama A048R - n/a; 8.5 to 9.0; 8.0 to 10
*as per tyre manufacturers listing
The above does seem to imply an 8.5 rear rim is a better choice than an 8, but it would be great if there's someone out there whose actually done it and can confirm it works!
Thanks for elaborating. Yes I did wonder if that 255 tyre width would be better with an 8.5.
Rim size to tyre size reccomendations seem to vary between tyre types/manufacturers and I was thinking that my 245s would perhaps also sit better on 8.5s.
In my search through past PH tyre thread, I know GreenV8S has posted on a few occasions in regard to the fact that (for track/sprint use) it's better not to 'over-tyre' the rims. Although, as someone else pointed out, the dynamics of the V8S rear swing-arm suspension vs. the Griff wishbone set-up may mean certain aspects of comparison are redundant.
Given that, on 17" wheels at least, a 225/45 seems to be the widest sensible choice, and for the benefit of anyone else pondering this at the moment (or trawling PH in future), these are the likely 'list 1B' suspects for 17" rear wheels at this time:
Manufacturer - rim size* for; 235/40; 245/40; 255/40
Toyo R888 - 8.0 to 9.0; n/a; 8.5 to 10
Kumho V70A - 8.5; 8.5; n/a
Yokohama A048R - n/a; 8.5 to 9.0; 8.0 to 10
*as per tyre manufacturers listing
The above does seem to imply an 8.5 rear rim is a better choice than an 8, but it would be great if there's someone out there whose actually done it and can confirm it works!
Hi
I'm looking into 17"s for my Griff and thought the received wisdom was for a 225/40/17 on the front rather than a 45 profile. This could cure your slight rubbing issue too perhaps?
The 3 companies I spoke to at the Autosport show recommended a 7.5 front and an 8.5 rear (on a 245/40/17 tyre) although added that an 8" rear could also work.
dumbfunk
I'm looking into 17"s for my Griff and thought the received wisdom was for a 225/40/17 on the front rather than a 45 profile. This could cure your slight rubbing issue too perhaps?
The 3 companies I spoke to at the Autosport show recommended a 7.5 front and an 8.5 rear (on a 245/40/17 tyre) although added that an 8" rear could also work.
dumbfunk
The 225/45 17 fronts do rub the arches, but only very slighly and on absolute maximum lock. The arches never bottom out over bumps when you're driving. It's not really an issue.
What I have seen on other cars (Mike Catania's 18" wheeled Griff IIRC) in the past, and I'm trying to avoid, is the rear tyres rubbing the arches under certain combinations of throttle/cornering. Hence the request for knowledge.
As Dumbfunk says, 8.5 wide rears seem favourite...
What I have seen on other cars (Mike Catania's 18" wheeled Griff IIRC) in the past, and I'm trying to avoid, is the rear tyres rubbing the arches under certain combinations of throttle/cornering. Hence the request for knowledge.
As Dumbfunk says, 8.5 wide rears seem favourite...
Been following this with interest. For the last three years I have been running A032r in a soft compound for the hill They were available in 245/45/16 and 205/55/15 so I fitted them to an original set of rims. The rears would definitely make a better footprint on an 8 inch rather than a 7.5 but Yokie said 7.5 was acceptable but not ideal. The improvement in grip over 1a rubber is astonishing, to the extent that you have to be careful after swapping the wheels back.
This year I hope to be running full slicks and my interest in this thread is not so much the rubber but wheels and offsets. To match the existing diameter and width I need 17x8 or ideally 8.5 rears and 16x7.5 fronts. There seems to be two choices Compmotive MO or Rimstock PR1.2. As the rubber should be the same size as original it should fit the arches. The bit I am worried about is offsets. What offsets are you people with 8 or 8.5 inch rims and reasonably standard width rubber running ? I had perhaps incorrectly assumed that if the rim is wider I should take half the extra width and remove it from the standard offset to put the centre back in the same place, but will it then clear the wishbones ? Richb seems to have gone the other way with a 40mm offset.
This year I hope to be running full slicks and my interest in this thread is not so much the rubber but wheels and offsets. To match the existing diameter and width I need 17x8 or ideally 8.5 rears and 16x7.5 fronts. There seems to be two choices Compmotive MO or Rimstock PR1.2. As the rubber should be the same size as original it should fit the arches. The bit I am worried about is offsets. What offsets are you people with 8 or 8.5 inch rims and reasonably standard width rubber running ? I had perhaps incorrectly assumed that if the rim is wider I should take half the extra width and remove it from the standard offset to put the centre back in the same place, but will it then clear the wishbones ? Richb seems to have gone the other way with a 40mm offset.
steve-v8s said:
The improvement in grip over 1a rubber is astonishing, to the extent that you have to be careful after swapping the wheels back.
It's interesting you should say that, because it is as I suspected. IIRC The TVRCC Speed Champ's give a 2.75% handicap for running list 1B tyres, as opposed to list 1A (i.e. standard road) tyres like S02s etc. and this seems to favour 1Bs.
I'm also only running at about 285 to 290 bhp, whereas there are one or two £10k+ motors (John Eales & Wildcat etc.) which are pushing out anything from about 310 to 340bhp. So I have to do something!
steve-v8s said:
There seems to be two choices Compmotive MO or Rimstock PR1.2. As the rubber should be the same size as original it should fit the arches. The bit I am worried about is offsets. What offsets are you people with 8 or 8.5 inch rims and reasonably standard width rubber running ? I had perhaps incorrectly assumed that if the rim is wider I should take half the extra width and remove it from the standard offset to put the centre back in the same place, but will it then clear the wishbones ? Richb seems to have gone the other way with a 40mm offset.
I think we've spoken before - despite your login, you run a Griff and not a V8S right? If so, you might want to look at going for 17" fronts, so you then have the option of upgrading the front discs & calipers in the future, if neccessary.
My current Goodyear F1 road tyres are on Compomotive MOs (front 7x17, rear 8x17) which are very nice (strong) wheels, although I believe the Rimstock/Team Dynamics Pro1.2 are supposedly lighter.
I plan to get the tyres off the rims to weigh my Compotives to check (don't laugh, I do think it's important to know these things!), but they tell me they are about 10kg, as opposed to about 9kg for the Pro1.2s. So there's probably little in it.
As for your question about the offset, I can't help you there really. It is something which has occurred to me, and I too would love to know the precise answer.
Yes I think we may have communicated before. I ran the V8s for a few years and then went to the Griff mostly to get away from the trailing arm suspension. 17 inch fronts do appear a sensible choice but the closest match to the road rubber sizes is achieved with a 16x7.5 inch. What offsets are your 8x17s ?
Weight is obviously a factor. I was chasing a rival last year and needed 0.2 second so took the passenger seat out between runs (didn't beat him but gave me something to do). Also I found that removing the radio, CD changer, 4 speakers and swapping the battery for a Red top 20 saved 23kg. Sadly I have more than gained that back now with the new roll over protection.
The 2.5% is probably about right I seem to remember that swapping between the S03s and A032s gained just over a second on a 38 second run, Having said that I did get to the limit of the S03s but there is probably a bit more to be squeezed out of the Yokies.
Weight is obviously a factor. I was chasing a rival last year and needed 0.2 second so took the passenger seat out between runs (didn't beat him but gave me something to do). Also I found that removing the radio, CD changer, 4 speakers and swapping the battery for a Red top 20 saved 23kg. Sadly I have more than gained that back now with the new roll over protection.
The 2.5% is probably about right I seem to remember that swapping between the S03s and A032s gained just over a second on a 38 second run, Having said that I did get to the limit of the S03s but there is probably a bit more to be squeezed out of the Yokies.
Steve,
Current sizes I'm running are:
FRONT: 7J17 et 28, 10.5kg tyres 225/45ZR17
REAR: 8J17 et 35, 10.6kg tyres 245/40ZR17
I've also removed the stereo (the car makes at least 104dB of racket, so you couldn't hear it anyway) and all the associated speakers, but in the 'road going' sprint/hill class, we are supposed to retain certain other niceties - carpets, all seats, glass cannot be swapped for perspex etc. - so I can't remove the passenger seating.
Might also try re-locating the battery to the boot, for better weight distribution though...
Current sizes I'm running are:
FRONT: 7J17 et 28, 10.5kg tyres 225/45ZR17
REAR: 8J17 et 35, 10.6kg tyres 245/40ZR17
I've also removed the stereo (the car makes at least 104dB of racket, so you couldn't hear it anyway) and all the associated speakers, but in the 'road going' sprint/hill class, we are supposed to retain certain other niceties - carpets, all seats, glass cannot be swapped for perspex etc. - so I can't remove the passenger seating.
Might also try re-locating the battery to the boot, for better weight distribution though...
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