Davey D
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| posted on 25/8/09 at 10:59 AM |
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Compomotive CXR
Im going to get another set of wheels for my VortX, so i can have R888 / track day tyres on one set, and some decent road / all weather tyres on my
other set.
At the moment ive got 7" x 15" TD Pro Race 1.2 with R888 (195x50r15 front, 205x50r15 rear).
The plan is to get some decent road tyres to replace these R888 when they are worn out, and get a set of 13" Compomotive CXR in black with R888
/ equivalents.
am i best to stick with 7" wide? what profile tyres should i get, and Where is the best place to buy them from?
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spdpug98
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| posted on 25/8/09 at 11:09 AM |
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I'm glad you asked this as it is exactly the same thing I want to do.
But I was possibly going to get the same size wheels and just put a set of wets on, but the 13" wheel sounds like a good plan
Will the 13's alter the gearing/top end much
My Blog: http://spdpug98.wordpress.com/
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hobbsy
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| posted on 25/8/09 at 11:21 AM |
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For CXR's email Compomotive directly and they'll sort you out with a price and availability etc.
For R888's or similar try camskill or even ebay on occasions.
I'd say 185/60-13 on a 6" rim (but watch the offsets) and if you want more width at the back still go for a 205/60-13.
If you cars been setup for larger tyres at the back you'll probably want to keep them or set it back up for the same size all round as changing
between the two will alter the ride heights front to rear (and the "wedge" which affects the balance of the car).
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Davey D
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| posted on 25/8/09 at 11:23 AM |
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The effect on the speed / gearing will be quite small, but each 13" wheel should be at least 1.5kg lighter than the 15" wheel
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hobbsy
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| posted on 25/8/09 at 11:35 AM |
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My 15x7 OZ's UltraLeggeras are approx the same weight as a 13x6 CXR.
As are TD Pro Race 1.2's I believe.
All weigh around 5kg's.
But normally I think you're right its just that OZ Super/UltraLeggeras and TD Pro Race 1.2's are very light for a cast 15x7 wheel and
CXR's are a little bit on the heavy side for a cast 13x6 (which should be closer to 4Kg than 5Kg).
Not sure exactly how the tyre weights effect things as you can never be sure how accurate they are and if they are worn etc but I think the tyres
people typically fit to 13's are a bit lighter but not by much. Varies make to make.
Fit ACB10s if you want light tyres as they are crossplies. But not much good in the damp/wet!
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progers
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| posted on 25/8/09 at 11:41 AM |
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Ideal sizes will 6" front and 7" rear assuming you are using 185/60 fronts and 205/60 rears. The 205 sit much nicer on a 7" rim,
although they will fit a 6".
Just a case a specifying the offset you need. Then give George Polley motorsport or compomotive (direct) a call to order them.
Depending on price you might want to give yokohama 048r a go as your trackday set. Better in the dry than R888 but probably worse in the wet.
ACB10's are great but very pricey.
Paul
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Davey D
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| posted on 25/8/09 at 11:52 AM |
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On the compomotive website the claimed weights for CXR are:
13 x 6 - From 4.5 Kg
13 x 7 - From 4.85 Kg
15 x 7 - From 6.7 Kg
On the Team Dynamics website the claimed weights for Pro Race 1.2 are:
15 x 7 - from 6.1kgs
so that is showing over 2kg difference per wheel between 13 x 6, and 15 x 7. even the Pro Race 1.2 is lighter than the same size CXR 
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hobbsy
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| posted on 25/8/09 at 11:59 AM |
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Well I've physically weighed OZ Superleggeras in 15x7 as just under 5Kg so that still compares favourably to a 13x7 CXR, i.e. within 100g which
you could almost have in balancing weights!
I also thought the 13x6's where heavier than that but TBH the set of those I weighed were version 1's and I think they made the version
2's (with dimples in the outer rim etc) a bit lighter.
Still all good as they are made in Wolverhampton which is near where I'm originally from rather than some Italian rubbish  But they do
unfortunately remind me of TSW Venoms which were popular >10years ago on Nova's etc!
When I was chatting with Barry (director of Compomotive IIRC) he didn't believe me that a 15x7 cast wheel weighed pretty much the same as his
most lightweight 13x6 wheel until I emailed him a photo of one sitting on some accurate scales.
[Edited on 25/8/09 by hobbsy]
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adithorp
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| posted on 25/8/09 at 12:14 PM |
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I'm running CXR's in 13x6.5 front with R888 in 185/60/13 and 13x7 rear with 205/60/13.
There's a slight reduction in diameter when compared with the 15's I've got running 205/50's and 185/55's.
Going via Compomotive direct was easiest I found. With anybody else your stuck with what they've got, size and offset wise.
The advantage of 13" is not just the weight reduction but also the weight is closer to the hub so allowing greater acceleration. The more
flexible sidewall also gives better grip and ride.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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paublo999
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| posted on 25/8/09 at 12:22 PM |
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I wouldn't recommend the ACB10's for road use. I run A24 compounds for the sprints and they tramline like a beggar on normal roads and
they do require slightly less camber than the Toyo's. Perhaps consider the SG compound unless wear is a big problem.
I run 13 inch 7j on the front for a 215 tyre and 8j on the back for a 245. Standard rear wings wont like anything beyond a 205 maybe 215 on the rears
and my wrap around wings needed some modification to take 215's and they still rub alittle on hard cornering. I realise this is way over the top
for road or even track use, but they do help with the sprinting/hills etc.
Cheers
Paul
My videos http://www.youtube.com/user/ninjabogeyracing
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hobbsy
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| posted on 25/8/09 at 01:26 PM |
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quote:
Originally posted by adithorp
The advantage of 13" is not just the weight reduction but also the weight is closer to the hub so allowing greater acceleration. The more
flexible sidewall also gives better grip and ride.
adrian
I'm not saying you shouldn't go for 13's its just some aren't as light as you think so the difference won't be night and
day if they weigh pretty much the same.
I've got some MB mag 13's for that at ~3.4Kg each
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alistairolsen
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| posted on 25/8/09 at 02:19 PM |
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MB mags are awesome but costly!
What are the lightest 13 inch cast rims? Pro race 2s?
Anyone tried weller steels for a comparison?
My Build Thread
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Davey D
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| posted on 25/8/09 at 03:52 PM |
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ive had another look on the Rimstock/Team Dynamics website, and found these which i think look good. ive always liked pinstripes around wheels, and i
think they would look great on my car
http://www.rimstock.co.uk/downloads/prorace12s-yellow.jpg
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