13 inches and what rubber

[Nick Whitlam]

I have just returned form my first sprint at Curborough with the club and thourally enjoyed it. But I realised that running 16 inch rims is not the way to go. I realise that I need some 13 inch rims. I was in class 4 amd would like to stay in this class until I get a bit more competative, so I don't intend to put slicks on. My question is should I stick with 13 X 6 all round or have 13x6 at the front and 13 x 7 at rear? And what is the best tyre to get as I am only going to use the 13 inch rims for track days and sprints?

[murph7355]

Not sure what class 4 means, but I think the general consensus is that if you have less than about 170bhp-ish, then you don't really need anything more than 185s all round and so 6"ers should be OK.

 

Of course generalising on such things is dangerous and will depend on the rest of the spec of your car...it'll also depend on how you like your car to handle.

 

As for which tyre, well I guess there must be a list of allowed tyres, and again I'm not sure what these are likely to be.

 

If ACB10s are on there, these are likely to be the grippiest in the dry but will need suspension changes (deDion ears etc) to get the most from them if you have radials now.

 

If Yoko 32Rs are on the list then these are great dry weather tyres but with (slightly) less outright grip than ACB10s.

 

If neither of these are present, what is?

[clarkey]

You'll need to use list 1a tyres for sprints - there are few choices in 13 inch however. Favourites are Bridgestone RE720s and Falken ZE502s.

[Big Brother]

Clarkey,

Is there a list of tyres for class 1A available on the net?

 

 

Steve

 

cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif

[clarkey]

I'm not aware of one. It is on page 278 of this years MSA Blue Book though.

 

These are the more popular 13 inch choices:

 

Avon CR322

Bridgestone Re720

Falken ZE502

Yokohama A509/510/520/539 (not sure which are available in 185/60-14 though.

 

So not much choice. Bracknell Tyres in Binfield, Berks do the Falken for about 30 quid each, so not bad. Graeme Finlayson swears by the Bridgestones (he is in the W*******d Speed Series). Most of the quick W*******d drivers use 15 inch wheels and Bridgestone SO2-PPs .

 

Scrubbed tyres are allowed, and this is supposed to help a lot.

 

List 1a is essentially proper road tyres. Include everything except for Avon ACB10s/CR500s, Dunlop Formula Rs, Yoko A021/32/38, ie, anything that suits a 7.

[Big Brother]

Thanks Clarkey

 

Steve

 

cool.gifScream...if you want to go faster!!!id=limegreen> cool.gif

[Alex Wong1697456877]

Nick,

 

To stay in class 4, the current favoured tyre is the RE720 which is available in 13".

 

If you plan to move up to class 5, then ACB10's are the best without doubt. If you're going to keep your 16" wheels for road use, then go for ACB10's in the softest compound (A24 I think - might be A42 - will have to look it up). Even without readjusting the camber, they're better than yoko's. They're not as bad in the wet as you may think as long there isn't any standing water to clear. I managed to post the fastest time in the 7's class on Saturdays BMMC sprint during the last wet session with ACB's. If you plan to use them in all conditions and want more durability, go for Yoko 021's or maybe even 032's.

 

If you're going for class 6, Avon do some very nice A40 compound slicks. I've yet to try these but I suspect they're amazing.

 

 

[Tim Sture]

FWIW - do not get Avon CR322s (like I have on my car), as their grip must be about at the bottom of the scale for list 1a tyres!

[Russ Jackson]

For road use I use Goodyear Ventura's 185/70 13 inch. Seem OK to me and steer much better than the Yokohama's I had before.

[EFA]

Alex,

 

You'll wear out A40's in about 5 laps!

 

Fat Arn

See another FAT ARNIE here

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[Alex Wong1697456877]

It depends on how many doughnuts I do to celebrate my victory!

 

If I ever move up to class 6, I'm going to need something like that to give people like Andy Ball and Keith Ritchie a run for their money. As for Dave K, I think we should have a class 7 for people who have done sub 57 runs. I'd love to see Richard Hay, Dave K, Tim Wilson and Clive Kenrick running in the same event but unfortunately two of them have sold their 7's!

 

Alex

[Nick Whitlam]

Thanks to you all for the advice I think I will probably go for the RE720's and mabe in a few months I get some ACB10s

[Paul Ranson]

Avon A39 is the 'normal' soft slick compound, A40 may be a little too soft, it's quite commonly used on the front of racing cars.

 

I found a set of 7x21 A39 on standard 6x13 Caterham wheels worked really well for casual hillclimb and sprint use on an otherwise roadgoing Caterham.

 

If you go non-roadgoing then you will need an MSA logbook, these are only a hassle if you need one tomorrow.....

 

Paul