What slicks for a Griff ?
Discussion
Not certain about where to post this, as it is Griff specific I will try here first.
Have got a bit confused trying to choose and source some slicks and rims to put them on for hill climbing.
The standard rubber on the car is 205/55/15 and 245/45/16 fitted to 15x7 and 16x7.5 rims. According to “the bible” this gives diameters of 606mm and 626mm. Being a bit simple I thought that it would be a case of finding some rubber that gave approximately the same diameter and width, in the right compound and then tracking down some rims to fit it to.
However the first problem is Radial or Crossply. Advice suggests that radials give a lot more grip for a given compound and are more tolerant of geometry settings. This makes the prospect of swapping between road tyres and slicks without altering the camber a lot more possible. However the disadvantage seems to be that when the limit is reached with a Radial the loss of grip is not a progressive as with a cross ply. In other words you get no warning until you actually hit the armco. Of the people asked, about half strongly recommend one and the other half equally strongly the other.
Looking round the paddock, Avons seem to be a popular choice and their 210/600/16 230/620/17 radials seem to roughly match the original rubber but the rears require 9 inch rims which seems to be a problem at the appropriate offset. In Crossply they list 7.5/23.0-16 and 8/24.0-17 which also come close and have the benefit of the rear fitting on an 8inch rim which is easier to find.
Yokie seem to have ideal sizes in radials but only the rears are in a soft compound.
Dunlop can offer 205/600/16 and 235/620/17 which again needs a 9inch rim.
If I increase the wheel size do I ideally (if it will fit) Alter the offset my half the difference to keep the track the same ?
Somebody must have done this already. The car has original 108 PCD studs. Any advice gratefully received.
Have got a bit confused trying to choose and source some slicks and rims to put them on for hill climbing.
The standard rubber on the car is 205/55/15 and 245/45/16 fitted to 15x7 and 16x7.5 rims. According to “the bible” this gives diameters of 606mm and 626mm. Being a bit simple I thought that it would be a case of finding some rubber that gave approximately the same diameter and width, in the right compound and then tracking down some rims to fit it to.
However the first problem is Radial or Crossply. Advice suggests that radials give a lot more grip for a given compound and are more tolerant of geometry settings. This makes the prospect of swapping between road tyres and slicks without altering the camber a lot more possible. However the disadvantage seems to be that when the limit is reached with a Radial the loss of grip is not a progressive as with a cross ply. In other words you get no warning until you actually hit the armco. Of the people asked, about half strongly recommend one and the other half equally strongly the other.
Looking round the paddock, Avons seem to be a popular choice and their 210/600/16 230/620/17 radials seem to roughly match the original rubber but the rears require 9 inch rims which seems to be a problem at the appropriate offset. In Crossply they list 7.5/23.0-16 and 8/24.0-17 which also come close and have the benefit of the rear fitting on an 8inch rim which is easier to find.
Yokie seem to have ideal sizes in radials but only the rears are in a soft compound.
Dunlop can offer 205/600/16 and 235/620/17 which again needs a 9inch rim.
If I increase the wheel size do I ideally (if it will fit) Alter the offset my half the difference to keep the track the same ?
Somebody must have done this already. The car has original 108 PCD studs. Any advice gratefully received.
When you run slicks, all the road suspension settings go outof the window and need to be readjusted to get the best out of them. Crossplies generally like 0 ish camber. Radials like as much camber as can be tolerated to give a good patch when cornering. Shocks and springs generally need to be far higher to help counteract the additional roll caused by the extra grip otherwise the contact patch is seriously reduced and the potential advantage not realised.
Second issue which is more important is that you need a very soft compound for sprints. Running race tyres will have a compound that needs to be warmed up before you get any grip which is not possible on a sprint. AVON tend to have the best selection here. Dunlop are another possibility.
The 520 is setup for crossply slicks and I don't mod the suspension for the road - just bolt a set of road tyres on it. I run crossplies as their camber setting is similar to that needed for the road. I use AVON slicks and Dunlop cut slick wets in the softest compound I can get. And yes you will need a set of wets as road tyres don't even come close.
Second issue which is more important is that you need a very soft compound for sprints. Running race tyres will have a compound that needs to be warmed up before you get any grip which is not possible on a sprint. AVON tend to have the best selection here. Dunlop are another possibility.
The 520 is setup for crossply slicks and I don't mod the suspension for the road - just bolt a set of road tyres on it. I run crossplies as their camber setting is similar to that needed for the road. I use AVON slicks and Dunlop cut slick wets in the softest compound I can get. And yes you will need a set of wets as road tyres don't even come close.
steve-v8s said:
Not certain about where to post this, as it is Griff specific I will try here first.
Have got a bit confused trying to choose and source some slicks and rims to put them on for hill climbing.
Have got a bit confused trying to choose and source some slicks and rims to put them on for hill climbing.
Dunlop DZ02J in the soft compound are worth a look, also cheap from MrTyremotorsport(dunlop dealer) at around £110+vat per corner. I use std chim rims which seem to be ok for trackdays, preserving the pretty(OZ) rims for club meets etc.
Thanks Steve, I was tempted to email the question directly to you as I figured it would be a race between you and Pete, I guess he will be along soon.
The problem is, as always, conflicting advice and I suppose part of it is because different drivers want different things from different cars, also different tyre people have different things to sell.
Appreciate what you say about the springs and dampers. The car is already fairly stiff, and I have adjustable dampers that should be good for going up a couple of spring rates. Also I have here in front of me a set of drop links that may help a bit with the roll.
Looking round the paddock the market does seem to be dominated by Avon, and there must be a reason for that. Why the difference in Camber requirements, is it because of side wall stiffness ? I suppose what you are saying tallies with other advice saying that the ideal set-up for radials would be closer to that for road tyres. What compound are you using ? The numbering system looks a bit odd A98 very soft, A91 Soft and A15 not quite so soft.
Thanks for the Toyo and Dzo2 suggestions, I am already running A032r which are list 1b, but I am looking for a bit more grip than road legal ones can offer.
The problem is, as always, conflicting advice and I suppose part of it is because different drivers want different things from different cars, also different tyre people have different things to sell.
Appreciate what you say about the springs and dampers. The car is already fairly stiff, and I have adjustable dampers that should be good for going up a couple of spring rates. Also I have here in front of me a set of drop links that may help a bit with the roll.
Looking round the paddock the market does seem to be dominated by Avon, and there must be a reason for that. Why the difference in Camber requirements, is it because of side wall stiffness ? I suppose what you are saying tallies with other advice saying that the ideal set-up for radials would be closer to that for road tyres. What compound are you using ? The numbering system looks a bit odd A98 very soft, A91 Soft and A15 not quite so soft.
Thanks for the Toyo and Dzo2 suggestions, I am already running A032r which are list 1b, but I am looking for a bit more grip than road legal ones can offer.
could always try Kumho V70 in soft. Its actually their F3 wet compound rubber on a List 1B carcass. Waaaaaaay softer than A032Rs in super soft or ACB10s (ive used them before) not as dear as slicks and road legal. On my car they are up to temp off the line (rears) and after first corner (fronts). Wont do 3 flat out laps of castle combe though before they start to overheat.
Closest think to slicks you'll find in my humble opinion.
Closest think to slicks you'll find in my humble opinion.
if ya not desperate (cant see why you would be as seasons a few months away...), id wait and speak to the 'techie' guys at the Autosport show. As you must be a speed licence holder due to you being a hillclimber, pop along on the thursday or friday and all the tyre firms have their techie guys on the stands. They will advise on all matters even down to pressures, tyre care and even differing compounds and their particular traits. Theres often new sizes and compounds launched at the show too, never know you may be in luck! Note most of the firms only have their gurus on the thurs and fridays, leave the normal staff to man the stands on the public days.
If you cant find the size you need, its better to get new wheels to suit, than buy a 'near enough' tyre to suit the rims you've got. You'll regret it in the long run (guess how i know :-)
If you cant find the size you need, its better to get new wheels to suit, than buy a 'near enough' tyre to suit the rims you've got. You'll regret it in the long run (guess how i know :-)
108mm is ford fit right? a set of 15" wheels to suit will open your choice of compounds up quite a bit. On my h/climber I currently use 205/50-15 on 7" fronts and 225/50-15 0n 8.5" rims. i will probably change the front rims to 7.5" to stretch the sidewalls a little over the winter tho.
Hello Guy's, I race with Michelin S9B slicks, I have to drive my car from my garage up the road to get it on the trailer. With slicks on cold from the garage I can tell you there is bugger all grip, far less then a basic tyre like a yoko 539 when they are cold, they take abiout 2 laps racing to heat up. I wouldnt hilclimb in them unless I had tyre warmers, which i dont. I'd say going to a hill climb and speak to competitors of similar vehicles to see what they are using is the best way. Or if you find a company who successfully races and preps hilclimb cars, just give them a call for advice.
Regards
rich
avon hillclimb slicks are what the majority of cars are using. I don't know of any class winner not on avons. I have tried hoosiers, dunlops and michilen and discarded them all for the ones that work straight off the line. As for camber settings etc, I run the same camber settings that I used on road tyres. Once again welcome to the minefield and look forward to seeing you in april.
Hi Ben
It seems that the choice has to be Avon Xplies provided I can find some rims to put them on without spending silly money. The possible exception is Yokie who have a product that is exactly the size I want for front and rear, but, all sizes are listed in a Hillclimb compound other that the rears I want. Really I put this post up in case it flushed out any rims, which may well be the case. Also got some useful PM from a couple of people.
Having carefully looked at video clips and pictures, most people do, as you say seem to be on Avons. Possibly with the exception of the Mini mob who seem to like the Hoosiers.
The rear dampers have been back to the manufacturer for a rebuild which should hopefully stop the rear end turning left when changing gear, and the Anti roll bars should have become a lot stiffer by April. Also looking at some slightly stiffer springs.
As usual the main hindrance to getting up the hill any quicker will be the driver.
It seems that the choice has to be Avon Xplies provided I can find some rims to put them on without spending silly money. The possible exception is Yokie who have a product that is exactly the size I want for front and rear, but, all sizes are listed in a Hillclimb compound other that the rears I want. Really I put this post up in case it flushed out any rims, which may well be the case. Also got some useful PM from a couple of people.
Having carefully looked at video clips and pictures, most people do, as you say seem to be on Avons. Possibly with the exception of the Mini mob who seem to like the Hoosiers.
The rear dampers have been back to the manufacturer for a rebuild which should hopefully stop the rear end turning left when changing gear, and the Anti roll bars should have become a lot stiffer by April. Also looking at some slightly stiffer springs.
As usual the main hindrance to getting up the hill any quicker will be the driver.
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