Rims & Tyres

[jrgibb72]

Hi all,

I've had some discussions in another place regarding rims / tyres and I'm struggling to find any clear answers. 

Owning an Elise the rims size is fixed and a fundamental part of what makes the car what it is - Lotus developed the handling right down to tyre development with people like Bridgestone, the Potenza for the Elise had a specific DOT code (the manufacturer identity part) specifically for the car. 

Given the nature of the Caterham the rim and tyre selection are a fundamental part of the setup I guess I'm surprised that there are so many rim (size and width) options each one will have significantly different impact on handling;

14” Classic silver alloy with 185/60 tyres 
13” Apollo silver alloy with Avon ZZS (6” front & 6” rear) 
13” Apollo silver alloy with Avon ZZS (6” front & 8” rear) 
13” Apollo black alloy with Avon ZZS (6” front & 6” rear) 
13” Apollo black alloy with Avon ZZS (6” front & 8” rear)
15” Orcus silver alloy with Avon ZZS 

It's only when you get up to the 620 that Caterham restrict the options to the 13" 8" rear and 6" fronts, but you can still go for the 15" Orcus - again I image you'll notice the difference on that car! 

Don't even start me thinking about the rolling diameter differences!!

From what I've discovered on t'interweb there's even a difference in the tyre weights ie the CR500 being considerably lighter than for instance Toyos and the ZZS (I think) all of which contributes to the unsprung weight. 

I've got the 15" rims (which look great I have to say) however are these the best for the car (Roadsport 150)?? I think they are 6.5" front and rear - I honestly don't know, I'll look tonight . . the spare is a 6.5". 

I guess after these ramblings my question is this - Do Caterham know / or recommend a particular Rim diameter and width size as being the optimum handling setup for the road?? PS this is not a questions about tyres it'll all get too messy 

I think my car looks great but is it on the wrong rims?? 

[Dixa1225]

CC will recommend the 13inch option . 

[punch]

As a class 3  competitor in the club speed championship with 150 hp ,the majority run 13" dia in  8" rears and 6" fronts , a minority run 7"fronts , or 6" rears . we all tend to run AVON ZZS tyres ,I currently have a set of Compomotive CXR rims /tyres for sale on pistonheads,.The 13 " tyres add addition suspension to the car, plus fill the rear arches nicely , but just for road use you might find rears a bit grippy but for track i think they are spot on and if i was using my car for road i would use 13 " dia.  

hope this helps, 

Philip

[Wrightpayne]

I think tyre availability, both in general and for sprinting does have a big part to play, as well as aesthetics. Some people like the look of the 16" HPC wheels but I read they spoil the handling of the car. Also ground clearance to avoid damaged sumps on raised cats eyes is also a consideration. Going lower may need suspension adjustments.

Perhaps drive a car with 13s and see what its like or borrow a set of wheels. Up to 200bhp 6" all around is fine.

Ian

[jrgibb72]

Philip,

Do you know the combined weight of the 13" 6" fronts plus a tyre? My spare 15" with a CR500 is around 13.7kg (13.9kg with the the two prong cradle still bolted to it). I'd be interested to get an idea of the comparable unsprung weight. If there's not a lot in it then it'll be about how the tyre wall of the 13" feels / contributes to the suspension plus any rolling diameter difference which I guess will be negligible with the correct tyre size.

J

[JNC]

Jason !! You have been on here long enough to know better lol Same old thinking split into two camps 15" and 13" that are obviously better it's like asking how long is the string . Basically it comes down to personal preference . Good luck 

[Tazio]

Question: How many racers use 15 inch wheels?

Answer: None

End of....

When you go to 13s you will probably need new front wing stays as those that are supplied for 15 inch wheels give too much clearance and look naff.

[punch]

Have weighed. Compomotive  CXR rims with Avon ZZS tyres

6 inch fronts with 185/13 tyres  12.2 kg

8” rears with 215 /13 tyres.   14.3 kg 

but I think it’s all about side wall flex because they feel so much better.

Regards

Philip

[JNC]

Answer: was the question about racers ?

Answer: NO 

End of...

As with ownership of Caterham 7 it's a personal thing See if someone will lend you a set of 13" and give them a try yourself . You won't get a unbiased answer on here .

 

[Tazio]

JNC, if you are going to parody my response at least get it right....

You seem to have made a typo..usually it is normally Question and Answer...., not Answer followed by Answer, still a little edit should sort that out

On the more salient point, you are right it is a personal preference, and after having cars on 16s, 15s, and 13s, for me, they work much better on 13s, the car is more communicative, irrespective of how the car is being used, road or race

End of.......

[JNC]

Ha ha   End of...........  Your opinion !

The point is there is no one size fits all 

End of.........