Wheel sizes for a Caterham BEC
Discussion
I know I know, it is wheel/tyre combos again. Sorry 
So, 170bhp ish GSXR1000 powered LA Caterham in the final stages of build.
Currently on 13x6 Minilites with 70 profile A021s.
Will probably be mostly track, with some road.
I am torn between sticking with the 6" all round, saving cost of new wheels (maybe getting them shotblasted and re-painted black sometime if I like 6"), and putting soft R888s on the front and meds on the rear. The Fireblade uses 205 rears as standard, but have heard a few Blackbird pilots say that 185s all round are nice for track work.
I know they are not all that light, or even Supalite, but MB Mag wheels are expensive and not sure they are going to like the potholes if I use on the road.
Or go for something like Compomotive CXRs, 6" front and 7" rear and fit CR500s for lightness.
So, should I go with existing 6" all round, and see what the handling is like, and then upgrade when have a bit more cash ? Or will 185 on 6" be just too undertyred to start with ?
Any thoughts, ta ?
So, 170bhp ish GSXR1000 powered LA Caterham in the final stages of build.
Currently on 13x6 Minilites with 70 profile A021s.
Will probably be mostly track, with some road.
I am torn between sticking with the 6" all round, saving cost of new wheels (maybe getting them shotblasted and re-painted black sometime if I like 6"), and putting soft R888s on the front and meds on the rear. The Fireblade uses 205 rears as standard, but have heard a few Blackbird pilots say that 185s all round are nice for track work.
I know they are not all that light, or even Supalite, but MB Mag wheels are expensive and not sure they are going to like the potholes if I use on the road.
Or go for something like Compomotive CXRs, 6" front and 7" rear and fit CR500s for lightness.
So, should I go with existing 6" all round, and see what the handling is like, and then upgrade when have a bit more cash ? Or will 185 on 6" be just too undertyred to start with ?
Any thoughts, ta ?
Hi Noger. I have a blade and that came with A048's that were 205's on the rears (7j) and 185's on the fronts (6j). Just Switched to 185's all round (avon zzr) and this has resulted in a noticable improvement in handling on the road, although this may have more to do with the sidewalls of the tyres being softer. Not tried it on the track with the new tyres but the car felt slightly overtyred to me before on the track. I only have a 140 bhp and I like to be able to provoke the rear end with the throttle.
One thing to bear in mind is the effect your tyre size may have on gearing. Going from 205's in 60 profile to 185's in a 55 profile has resulted in me losing some top end, about 6%. Should be good for hillclimbs but makes things even more manic on the road.
One thing to bear in mind is the effect your tyre size may have on gearing. Going from 205's in 60 profile to 185's in a 55 profile has resulted in me losing some top end, about 6%. Should be good for hillclimbs but makes things even more manic on the road.
balance of grip vs power hence adjusability on the throttle and smiles
per mile
downside of lower grip front tyres is that you can't stop the buggar .....
one f1 driver back in the day said
that adequate power vs grip is when you wheelspin in every gear - to achieve this you could acquire 400bhp or you could fit 185 section zzr's or you could only drive in the wet
per mile
downside of lower grip front tyres is that you can't stop the buggar .....
one f1 driver back in the day said
that adequate power vs grip is when you wheelspin in every gear - to achieve this you could acquire 400bhp or you could fit 185 section zzr's or you could only drive in the wet
Noger said:
Think there was a cheap RS V8 on PH recently, £25,000. Bargain.
The RST's not for me thanks. I think the one you mention was 27 and a half K, still more expensive than a new 2.8 H1. Allbeit with 400ish hp, and not 500. (A bit academic really anyway!)Anyway, sorry to take your thread OT. Can't help with weights I'm afraid.
I ran an R300 which was around the same power as your car, with the 175/205 tyre combo, and 6/8 inch 13"s, and it handled great. Steerable on the throttle, basketloads of laughs!
Of course the balance of you car will be different to a CEC.
have you calculated the theoretical top speed with the gixer and i assume 3.54 axle if its a live as you mentioned ?
i reckon you're biggest issue will be too short gearing - 205's over 185's will help at the rear - but before you contemplate buying new wheels - do the maths assuming you are on 13" wheels ? as you may even end up needing larger diameter wheels to get the top speed where you want it
i reckon you're biggest issue will be too short gearing - 205's over 185's will help at the rear - but before you contemplate buying new wheels - do the maths assuming you are on 13" wheels ? as you may even end up needing larger diameter wheels to get the top speed where you want it
Yes, I have a Quaife ATB one but I am sure there are others available.
With some extra oil, oil seals on the baffle plates, and a few other mods I hope it won't break
I think it should work OK with my injected K2 lump. Is quite old, but the technology to work around all the "clever" bits Suzuki-san now puts on their bike engines seem to lag by a few years which is useful. So we can override the TRE and the ECU, but what I really want is something to override the STVA when it breaks. We have removed the butterfly valves, but the actuator is known to be flaky and will throw a code and go "limp home" when it does. Would be nice to have something like the EXUP dummy unit on the Yamaha to replace it with.
Anyway, enough techy engine talk
Current thoughts, to make the unsprung weight as low as possible (within reason) is some 6X13 Ultralights (from Superlite) and CR500s in 175/55/R13 all round. Too skinny ?
With some extra oil, oil seals on the baffle plates, and a few other mods I hope it won't break
I think it should work OK with my injected K2 lump. Is quite old, but the technology to work around all the "clever" bits Suzuki-san now puts on their bike engines seem to lag by a few years which is useful. So we can override the TRE and the ECU, but what I really want is something to override the STVA when it breaks. We have removed the butterfly valves, but the actuator is known to be flaky and will throw a code and go "limp home" when it does. Would be nice to have something like the EXUP dummy unit on the Yamaha to replace it with.
Anyway, enough techy engine talk
Current thoughts, to make the unsprung weight as low as possible (within reason) is some 6X13 Ultralights (from Superlite) and CR500s in 175/55/R13 all round. Too skinny ?
sounds good - i hope the gixer unit does prove reliable.. its a stonking engine.
The 175 alround will be 'fun' but I think for ultimate grip I'd go wider on rear...
I've tried 185s alround on mine - which for general use and tracks days etc was 'fun' as it moved around a bit more, and with the slightly reduced gearing, picked up quicker.. but 205s on the back gave it slightly better grip off the turns - only resulting in a few tenths per lap in the real world - so if you're not racing probably no big deal... also if you go same size alround you can rotate tyres etc and ultimately its cheaper !
The 175 alround will be 'fun' but I think for ultimate grip I'd go wider on rear...
I've tried 185s alround on mine - which for general use and tracks days etc was 'fun' as it moved around a bit more, and with the slightly reduced gearing, picked up quicker.. but 205s on the back gave it slightly better grip off the turns - only resulting in a few tenths per lap in the real world - so if you're not racing probably no big deal... also if you go same size alround you can rotate tyres etc and ultimately its cheaper !
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