radial vs cross ply... and tyre choice ?
Discussion
hi Guys,
I'm assuming the radicals are generally set up to run radial tyres, in which case if i wanted to run sticky road treaded tyres (to suit a certain championship i am looking at) I woudl need to be looking at Kumho, Toyo, Yoko's etc ???
anyone had any specific eqperience of these ?? the Kumho looks to be a good tyre... the ACB10 (cross ply) seems the best traded tyre for circuit racing - but not relaly keen to change the set up of the car for cross ply's - and in turn have to run cross ply slicks etc... and woudl also be a pain if i wanted to run in the rarical clubmans cup etc..
the actual diameter/circumference of the tyres woudl need to be as close to the std dunlop slicks too, in order to not affect ride height/rake... or clearance issues with bodywork...
Mark.
I'm assuming the radicals are generally set up to run radial tyres, in which case if i wanted to run sticky road treaded tyres (to suit a certain championship i am looking at) I woudl need to be looking at Kumho, Toyo, Yoko's etc ???
anyone had any specific eqperience of these ?? the Kumho looks to be a good tyre... the ACB10 (cross ply) seems the best traded tyre for circuit racing - but not relaly keen to change the set up of the car for cross ply's - and in turn have to run cross ply slicks etc... and woudl also be a pain if i wanted to run in the rarical clubmans cup etc..
the actual diameter/circumference of the tyres woudl need to be as close to the std dunlop slicks too, in order to not affect ride height/rake... or clearance issues with bodywork...
Mark.
Interesting question, but here's my 2 peneth.
I have run 4 sets of Kumho V70 soft grade (med and hard available in 16/15/13'' rim dia)
I have run these radials on a 1973 Porsche 911 and Impreza, both cars for radials.
The Impreza i ran in my final year hillclimbing in the car on cross ply Avon hillclimb slicks. I reduced the camber on all corners from 3.5 neg to 1.25 neg and the car was stunning.(traction/brakes/stability)
I felt the crossply slicks had stiffer walls and certainly weighed about half the Kumho weight.
The 911 is 1000Kg and the Impreza 1250Kg so both needed stiff side walls.
This year i ran the 911 on the Kumho V70 soft on 3000 road miles and 10 hillclimbs, but for track you will need medium grade.
Stunning tyre in the rain, nearly bagged FTD at one hillclimb in the Impreza on Kumho's agaist wet slicks/single seaters.
Maybe this helps you.
The Kunho V70's are List 1B MSA Book.
Graham.
I have run 4 sets of Kumho V70 soft grade (med and hard available in 16/15/13'' rim dia)
I have run these radials on a 1973 Porsche 911 and Impreza, both cars for radials.
The Impreza i ran in my final year hillclimbing in the car on cross ply Avon hillclimb slicks. I reduced the camber on all corners from 3.5 neg to 1.25 neg and the car was stunning.(traction/brakes/stability)
I felt the crossply slicks had stiffer walls and certainly weighed about half the Kumho weight.
The 911 is 1000Kg and the Impreza 1250Kg so both needed stiff side walls.
This year i ran the 911 on the Kumho V70 soft on 3000 road miles and 10 hillclimbs, but for track you will need medium grade.
Stunning tyre in the rain, nearly bagged FTD at one hillclimb in the Impreza on Kumho's agaist wet slicks/single seaters.
Maybe this helps you.
The Kunho V70's are List 1B MSA Book.
Graham.
cheers Graham..
they do look to be a good tyre.. although teh profile seem to be low - 50 fronts and 45 rear so may affect ride height/rake if used on the same day as slicks etc.. needs some more research i think..
i think dunlop do a tyre - Z 01s ? thinking out loud with that one as i haven;t researched it properly.....
they do look to be a good tyre.. although teh profile seem to be low - 50 fronts and 45 rear so may affect ride height/rake if used on the same day as slicks etc.. needs some more research i think..
i think dunlop do a tyre - Z 01s ? thinking out loud with that one as i haven;t researched it properly.....
Mark, I think it depends on the regs of the championship you intend to run in. The ACB10's would probably be the best dry road-legal tyres you could get. It should be very easy to set the Rad up for the right geo for them. As the rad is similar in weight to a light caterham, there should be nothing to go wrong provided you can get ACB10s in suitable sizes. Somehow though, I doubt that ACB10s will be allowable in the class you want!
Bert
Bert
hi bert - they are allowed ik.. just have to be treaded tyres - the fast guys in class are alreday using them..
I think the radical is set up for radials though.. and if i want to do the likes of the clumans cup round (s) etc it would mean a total change to set up - camber etc...
i may well just change to cross ply's and be done with it !! be interesting if anyone runs their radical on cross ply slicks rather than radial - and for what reasons...
I think the radical is set up for radials though.. and if i want to do the likes of the clumans cup round (s) etc it would mean a total change to set up - camber etc...
i may well just change to cross ply's and be done with it !! be interesting if anyone runs their radical on cross ply slicks rather than radial - and for what reasons...
Mark
Hi. If you are able to change camber relatively quickly, then this is all you should need to do.
Rather than rely on a "set your camber to X degress" approach, if you get hold of a tyre temp probe (the IR ones are cr@p IMHO), then you can set the camber accurately once you have the heat profile correct over the width of the carcass.
Cross plies typically run with either 0 or almost zero neg camber, whereas the same car running radials may require say -2 degrees.
Not sure if ACB10 are available in a very wide section in a 13" size though?
Hi. If you are able to change camber relatively quickly, then this is all you should need to do.
Rather than rely on a "set your camber to X degress" approach, if you get hold of a tyre temp probe (the IR ones are cr@p IMHO), then you can set the camber accurately once you have the heat profile correct over the width of the carcass.
Cross plies typically run with either 0 or almost zero neg camber, whereas the same car running radials may require say -2 degrees.
Not sure if ACB10 are available in a very wide section in a 13" size though?
thanks dave - the kumho's do seem to get a good rep... was that a typo or is there a 700 as well as the V70's i have heard/read about ??
the only disadvantage i can see at this stage is that they are quite a low profile - so may upset the ride height/rake relative to slicks.. but need to compare like with like...
the only disadvantage i can see at this stage is that they are quite a low profile - so may upset the ride height/rake relative to slicks.. but need to compare like with like...
Of my 4 sets I've been through one was V700 and the others moulded as V70. Never got to the bottom of that.
I doubt the ACB's come wide enough and are mainly a FF control tyre?
I think the Dunlops are too close to the Track Day tyre application but I've seen some very fast hillclimb runs on them.
The Kumho web site is quite good.
I doubt the ACB's come wide enough and are mainly a FF control tyre?
I think the Dunlops are too close to the Track Day tyre application but I've seen some very fast hillclimb runs on them.
The Kumho web site is quite good.
I ran in the Berkett a few weeks ago using ACB10's on my SR4. We just changed the camber and the handling was fine. The handling was very progressive with just a bit more movement than slicks. I got the biggest size they do and they fitted fine over my 8's and 10's rims. Rolling circumference was similar so it didn't affect the rake/ride height. The medium compound wore pretty well also, they still have plenty of life left in them,
Jon
Jon
thanks guys..
the kumho looks good.. apart from the low profile of the tyre itself..
the diameter of the 235/45/13 is only 536mm whereas the diameter of their slick is 573mm and the dunlop slick is 575mm so way too far apart for what i want - i.e. to run on the same day on treaded tyres and slicks...
i may end up with the acb10 and a cross ply slick for that reason, but will then need a road legal wet too - as the acb10 is pretty useless in the wet..
aggghhhhhhhhhhhhhhhhhhhhhhh
the kumho looks good.. apart from the low profile of the tyre itself..
the diameter of the 235/45/13 is only 536mm whereas the diameter of their slick is 573mm and the dunlop slick is 575mm so way too far apart for what i want - i.e. to run on the same day on treaded tyres and slicks...
i may end up with the acb10 and a cross ply slick for that reason, but will then need a road legal wet too - as the acb10 is pretty useless in the wet..
aggghhhhhhhhhhhhhhhhhhhhhhh
yea - it will run ok bert, but really only as a wet.. most (all?) wet tyres are radial anyway - i think..
the CR500 is supposedly the radial equivalent of the ACB10 - but in reality the dry weather performance is not on a power with it - again from what i gether..
without about 10 sets of wheels, the various tyres.. and a few days on track myself its all here say and banter anyway really.. just trying to get as much past experiences from folk as i can to save inventing the wheel so to speak !
the CR500 is supposedly the radial equivalent of the ACB10 - but in reality the dry weather performance is not on a power with it - again from what i gether..
without about 10 sets of wheels, the various tyres.. and a few days on track myself its all here say and banter anyway really.. just trying to get as much past experiences from folk as i can to save inventing the wheel so to speak !
yep, I have run a Caterham on ACB10s and CR500s as wet tyres. Interestingly in wet conditions that are not standing water, the ACB10 is not bad. The CR500 is better in the wet, but of course in the dry, the ACB10 is a fantastic tyre. In the wet, the CR500 is rubbish in comparison with a race wet, but of course not road legal.
When I was contemplating a road legal radical, I was thinking of going the ACB10/CR500 route.
Bert
When I was contemplating a road legal radical, I was thinking of going the ACB10/CR500 route.
Bert
beware of using an ACB10 in the damp at the Ring!yep the Kumho tyre does sound interesting and the guy was helpful i spoke too, but even he commented that the profile was very low - hence the diameter is much lower than the other radial tyres - meaning it woudl be nigh on impossible to run those and any radial slick without lifting the ride height quite a bit for the Kumho's
the diameter of the rear kumho is 536mm, most slicks are ~575mm
What i am planning to do next year is run in two different classes on the same day - and qual and race sessions coudl potentially be only 10 mins apart - so i will have no time other than change wheels, refuel and basic check over..
Will see what Dunlop come back with - if they have a sticky treaded tyre within the ballpark diameter it may be ok... but they sure must keep it a good secret !!
Mark.
the diameter of the rear kumho is 536mm, most slicks are ~575mm
What i am planning to do next year is run in two different classes on the same day - and qual and race sessions coudl potentially be only 10 mins apart - so i will have no time other than change wheels, refuel and basic check over..
Will see what Dunlop come back with - if they have a sticky treaded tyre within the ballpark diameter it may be ok... but they sure must keep it a good secret !!
Mark.
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