Wheel and Tyre sizes please
Discussion
Well, a couple of years ago, Our Friends In Peterborough told me that Prosports run on 8" fronts with 190/530 x 13 and 10" rears with 230/570 x 13 Dunlops.
As I run on Avons, I use 195/530R13 on the front and 250/570R13 at the other end!
Darren should be along in a mo to tell you about PR6s
As I run on Avons, I use 195/530R13 on the front and 250/570R13 at the other end!
Darren should be along in a mo to tell you about PR6s
nick997 said:
SR4, 7" and 9" wearing 175 and 205, optional 8" and 10" wearing ???. Splitpin will be able to answer the latter.
As Nick says, in terms of the SR4, with the standard width wheels i.e. 7" - as they are usually called - fronts and 9" - as they are usually called - rears, 175/535/13 Dunlops and 205/570/13 Dunlops respectively are the factory fit; word of caution on those inch widths > these usually refer to one piece cast wheels like Compomotive CXRs, the widths and offsets can be different for three piece wheels. With the wider wheels i.e. 8" - as they are usually called - fronts and 10" - as they are usually called - rears, 190/535/13 Dunlops and 230/570/13 Dunlops are the correct sizes respectively.The way I read it, narrow wheel option only to count in the Quaife Cup Championship for SR4s etc, wider wheel would leave one in the non-counting Invitation Class.
Michelin do have sizes which are dimensionally compatible with the wider wheel option, but not the standard wheel widths, particularly the rears which are in effect Radical specific. How do the Michelins compare with the Dunlops? The only way to tell would be to get someone like JW on two fresh sets and find out, but I suspect that as good a tyre as Michelin is, the Dunlop would have a pretty clear maximum attack advantage; afterall, there's a long development track record between R & D.
As LCM notes, a lot of the sprint and hillclimb chaps use 250 Avons on the rear on 10" wides; these certainly need watching on an SR4 which has a fairly wide rear bodywork wheel arch flange and tends to 'hood' the wheel more than a Clubsport / Prosport on compression; on an SR4, to run low and avoid rubbing, the negative offsets may well need reducing for these very wide tyres.
Wonder why 'without Radical' JP wants these details for every car Radical have made / are making?
Oh! Just to pick up a point that Trevor's reply brought back to mind (I blame advancing old age and a surfeit of good claret).
When I first put 8s and 10s on my Prosport everything looked fine with the car on chassis stands - loads of clearance everywhere.
BUT running it in anger on sticky Avons resulted in the webs on the bottom wishbones (where the dampers attach) planing geat lumps out of the inner wheel rims such that I had to have all my wheels re-rimmed (with a resulting major contribution to Harry's retirement fund). Fitting 3mm spacers stopped this but under load there is still only just room for a fag paper 'tween web and wheel.
An expensive reminder not to rely on static clearances holding up under load.
When I first put 8s and 10s on my Prosport everything looked fine with the car on chassis stands - loads of clearance everywhere.
BUT running it in anger on sticky Avons resulted in the webs on the bottom wishbones (where the dampers attach) planing geat lumps out of the inner wheel rims such that I had to have all my wheels re-rimmed (with a resulting major contribution to Harry's retirement fund). Fitting 3mm spacers stopped this but under load there is still only just room for a fag paper 'tween web and wheel.
An expensive reminder not to rely on static clearances holding up under load.
Darn it, got the old age, missed out on the claret!
Been there, done that, got the tea shirt(s) >
Had that problem with my 10" rears, but spotted it before driving it so didn't do anything other than minor cosmetic; cured mine by just taking a couple of mm off the free front tubular end of the wishbone with an angle grinder; with (thicker flange cast) CXRs, there's also a contact problem with the top outer wishbone to hub bolt as the wider wheels go over it, whereas the 9" don't; only cure for that is a special low height replacement bolt from Radical ......... let's just say a rather expensive bolt.
Also had that web contact problem on 8" fronts, but only when full lock backing into pits etc, not driving; best way to avoid that without adjusting offsets with spacers etc is to fit lock reducers ........ simple and relatively inexpensive things available from Radical. Only downside is that it makes what were three point turns about five point turns.
Been there, done that, got the tea shirt(s) >
Had that problem with my 10" rears, but spotted it before driving it so didn't do anything other than minor cosmetic; cured mine by just taking a couple of mm off the free front tubular end of the wishbone with an angle grinder; with (thicker flange cast) CXRs, there's also a contact problem with the top outer wishbone to hub bolt as the wider wheels go over it, whereas the 9" don't; only cure for that is a special low height replacement bolt from Radical ......... let's just say a rather expensive bolt.
Also had that web contact problem on 8" fronts, but only when full lock backing into pits etc, not driving; best way to avoid that without adjusting offsets with spacers etc is to fit lock reducers ........ simple and relatively inexpensive things available from Radical. Only downside is that it makes what were three point turns about five point turns.
I know an old topic. I have a 2004 Radical Sr3 with the 260hp engine. I currently have
Front Tires that are Hoosier's 200/580/15 and rear tire Hoosier ) 265/605/16. I want to go with Michelins and found a set that are 18 / 58 - 15 for the front and 23 / 61 - 16 for the rear. How much is this off and how do you make the conversion with the different number system?
Front Tires that are Hoosier's 200/580/15 and rear tire Hoosier ) 265/605/16. I want to go with Michelins and found a set that are 18 / 58 - 15 for the front and 23 / 61 - 16 for the rear. How much is this off and how do you make the conversion with the different number system?
Perhaps not quite as confusing as it first appears, the main difference there is just cm vs mm i.e. just x10 to get representative figures. However the Michelin numbers often don’t compare directly to the actual sizes, check here for actual mm size and other useful information.
http://michelinmotorsport.com/content/download/116...
To work out the various circumference/gearing differences there are a few tyre size calculators online which can be helpful (google search) but it’s simple enough once you get your head around the sizes.
Rgds,
Dunc.
http://michelinmotorsport.com/content/download/116...
To work out the various circumference/gearing differences there are a few tyre size calculators online which can be helpful (google search) but it’s simple enough once you get your head around the sizes.
Rgds,
Dunc.
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