Ivan
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| posted on 14/2/12 at 07:25 PM |
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Impact of tyres on lap times
My Cobra currently runs very ordinary low performance 15 x 295 X 60 tyres on the back and 235's on the front - the only choice I have for the
wheel size. I have often wodered if changing to 17 or 18 inch wheels and some premium tyres in similar widths will give significantly improved lap
times.
On a 1' 30" lap how many seconds do you think I would gain from such a change. I don't think I will find R888s in those sizes so
would be limited to the better Pirellis or Yokos.
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bi22le
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| posted on 14/2/12 at 08:12 PM |
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It will obviously make a diference because sticky black stuff is better than non sticky stuff.
From the track days I have done the biggest lap time gains (or losses depending on half empty or half full!!) I have found is improving my skill, my
familiarity with the car, my familiarity with the same circuit and setting the car up better.
I think that if your maxed out on the above then invest in new rubber but with the sizes your talking about thats a lot of monies. If your not maxed
out on the above then I would do the above first unless your tyres are really bad or deep down you really want to change your wheels!!
From what I have read on here lower profile tyres dont work as well on lighter, stiffer set up cars as the tyre wall deflects and increases contact
patch. I am not sure if the same applies to heavier brute V8 Cobras, someone will answer that one soon.
Good luck with the need for speed.
This will be an interesting thread, I am always ears open on how to get round a track faster.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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LBMEFM
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| posted on 14/2/12 at 09:05 PM |
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Lydden lap times in my MK Indy-Blade on Yoko's was circa 50 sec's, changing to R888's resulted in an immediate 48 sec's and
the car felt so much more stable.
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will121
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| posted on 14/2/12 at 09:22 PM |
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If you after out and out best lap times then if you go to 18 inch rims there are lots of options of slicks, I was amaised at the difference but be
ware better gripping tyres will highlight over weaknesses like suspension, bearings, oil etc
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Benzo
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| posted on 15/2/12 at 12:29 AM |
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quote:
Originally posted by will121
If you after out and out best lap times then if you go to 18 inch rims there are lots of options of slicks, I was amaised at the difference but be
ware better gripping tyres will highlight over weaknesses like suspension, bearings, oil etc
Is this true? I certainly won't be changing my 13's to 18's to chase faster laptimes!! 
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MikeRJ
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| posted on 15/2/12 at 09:15 AM |
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quote:
Originally posted by will121
If you after out and out best lap times then if you go to 18 inch rims there are lots of options of slicks, I was amaised at the difference but be
ware better gripping tyres will highlight over weaknesses like suspension, bearings, oil etc
There is at least as much choice in 15" rim sizes, if not more. Every stage rally I go to there is a van selling slicks and mounting tyres for
people, and I reckon 90% of the tyres he stocks and sells are 15".
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Ivan
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| posted on 15/2/12 at 12:14 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by will121
If you after out and out best lap times then if you go to 18 inch rims there are lots of options of slicks, I was amaised at the difference but be
ware better gripping tyres will highlight over weaknesses like suspension, bearings, oil etc
There is at least as much choice in 15" rim sizes, if not more. Every stage rally I go to there is a van selling slicks and mounting tyres for
people, and I reckon 90% of the tyres he stocks and sells are 15".
Maybe in Britain but there is very limited availability of of tyres in 15" that are +260 width in South africa and are suited for road use. 
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Fred W B
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| posted on 15/2/12 at 06:16 PM |
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On a 1 min 20ish lap here in PE, going from good road tyres to slicks is reckoned to take 2 seconds off the lap time. So at a guess I would expect to
see a minium of 1. 5 sec to maybe 2 going from ordinary to good road tyres.
Cheers
Fred W B
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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Ivan
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| posted on 15/2/12 at 07:37 PM |
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Thanks for that all - I guess what I will do is spend more time on the track with what I've got, and concentrate on suspension and my own
driving and once I am happy with my own performance, and feel I have suspension settings good enough, then review the tyre situation because as said
they are the most expensive of the options and best left to last when I can get the most benifit from them. It's just that new wheels are such
fun and can totally change the look of the car.
Once I have the new tyres I realise that I will most probably have to change suspension settings again.
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