FIA Tyre sizes

289, FIA & Daytona topics
SiJackson
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FIA Tyre sizes

Post by SiJackson » Tue Mar 05, 2019 2:03 pm

I'm quite interested to know what tyres you guys are fitting to FIA rims, what tyres and how you find them? To be fitted to a Hawk of course. Is anyone using the Avons?

Thanks
Si

peterc
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Re: FIA Tyre sizes

Post by peterc » Tue Mar 05, 2019 5:38 pm

Si,
It depends what width wheels you intend to use.
Mine are the early spline drive 6.5” front and 8.5” rear. So tyres are 215 x 60 front and 245 x 60 rear ( the nearest I could get to 255 x 60) .
Yes, I use the Avon’s CR6 ZZ which are not cheap but are a confidence boost over normal road tyres. Avon only give them a short life span!
The newer FIA’s in the club use pin drive 7.5” front and 9.5” rear and use 225 x 60 and 275 x 55.
Peter C

KevinW
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Re: FIA Tyre sizes

Post by KevinW » Tue Mar 05, 2019 6:04 pm

The best value V-rated tyres for knock-ons are North Hants Tyres' Galaxies, based just outside Aldershot,
If you don't like the lettering they can be fitted with it on the inside edge.

e.g.
http://www.northhantstyres.com/main-tyr ... R-RWL.html

All 60 profile, and just check as some sizes are not V-rated.

Getting good reviews on 'that other forum' ;)
http://www.cobraclub.com/forum/showthread.php?t=60916

peterc
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Re: FIA Tyre sizes

Post by peterc » Tue Mar 05, 2019 8:23 pm

Interesting.
That option wasn’t around when I built my car in ‘99 and I was not aware of them two years ago when I realised the Pirelli’s were well past their best and needing changing regardless of tread depth.
Peter C

Jerryedmans
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Re: FIA Tyre sizes

Post by Jerryedmans » Wed Mar 06, 2019 12:47 am

Just out of interest what tyre pressures are you running on these?
Cheers
Jerry

peterc
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Re: FIA Tyre sizes

Post by peterc » Wed Mar 06, 2019 7:57 am

Jerry,
Assuming you were asking after pressures with the Avon’s I use 25 psi all round.
When I had them fitted at the Avon factory they asked for my preferred pressure and I quoted the same as I had been using for the Pirelli’s for 15 years namely 23 front and 18 rear. They were very surprised as they would have suggested 30 psi.
In checking the tread depth across the old tyres agreed that they had worn correctly. Accepting that the car only weighs 1000 kgs they suggested I experiment with pressures but mindfull of reducing too much. Other members on similar Avon’s use 26 psi but I am happy for them to be a tad lower.
Peter C

SiJackson
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Re: FIA Tyre sizes

Post by SiJackson » Thu Mar 07, 2019 12:24 pm

I had a chat with Gerry and we threw some ideas around.

Being in a rural area with cack roads, and therefore running generous ride height, we decided to try 215/70R15 Avons. The rolling diameter of the 70 profiles is the same as the 245/60 rears at 678mm. They fill the arch nicely and have a really nice period look. There was a slight issue with the tyre catching the front valance and lower part of the arch on lock. Air saw and the sander made short work of that and there is now plenty of room. :D

ImageUntitled by simon jackson, on Flickr

SiJackson
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Re: FIA Tyre sizes

Post by SiJackson » Thu Mar 07, 2019 12:26 pm

peterc wrote:
Wed Mar 06, 2019 7:57 am
Jerry,
Assuming you were asking after pressures with the Avon’s I use 25 psi all round.
When I had them fitted at the Avon factory they asked for my preferred pressure and I quoted the same as I had been using for the Pirelli’s for 15 years namely 23 front and 18 rear. They were very surprised as they would have suggested 30 psi.
In checking the tread depth across the old tyres agreed that they had worn correctly. Accepting that the car only weighs 1000 kgs they suggested I experiment with pressures but mindfull of reducing too much. Other members on similar Avon’s use 26 psi but I am happy for them to be a tad lower.
Peter C
I plumped for 28psi, a little lower than the recommended 30, as its such a light car. I may go a little lower like your good self

Jerryedmans
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Re: FIA Tyre sizes

Post by Jerryedmans » Sat Mar 09, 2019 12:56 am

Cheers - I think I'll give slightly lower pressure a go too and see how it affects ride.

peterc
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Re: FIA Tyre sizes

Post by peterc » Sat Mar 09, 2019 7:45 am

I agree on the 215 x 70’s. I had thought of those but at the time concentrated on having 60% all round.
Gerry’s opinion is that we all run our cars too low so suggest you let the car settle before considering lowering.
Having the car slightly higher will only help with the IVA height requirement for the lighting. The rear fog often finds itself a few mm too low despite being tight up to the valance.
On the pressures I suggest you try them on varying road surfaces. I’m sure you will soon be down to 25 to have a modicom of comfort.
Peter C

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