Citroen Specials Club - the club for all lightweight cyclecars

Hi all

My car is fitted with Austin Seven 17" wire wheels and had fitted some Chengshin Chinese motorcycle tyres (3.25x17). The tyres have no sidewall strength whatsoever and the car understeers badly. Has anyone else got 17" wheels fitted and if so what brand of tyre do you use?

I have actually bought some proper car tyres from Longstone tyres, designed for the Austin 7 wheel but if I fit them they will foul the mudguards because of their higher profile, the next alternative is bigger fenders and brackets which is going to prove costly.

Thanks

I run these wheels on my Pembleton.

The tyres I have are the Excelsior 400/425 17.

They are big tyres but look the part. They do gear the car up a fair bit too from the standard 2cv wheels, which is only a good thing. Corner holding seems unchanged from the 2cv wheels, apart from the lighter feel due to the increased rolling diameter. I have a speed/rev calculator I've made. What gearbox do you have? What exact brand/size tyres are on currently?

I had some new brackets made up by Tonny Visser and I'm using some alloy mudguards from "feked" that are used on the front of classic bikes like the BSA/Norton's.

I'll upload some images tonight....

Thanks for the info' really appreciated.

I've fitted the Longstone 400/425-17's and they look really smart, the old Chengshin Chinese motorcycle tyres (3.25x17) are now binned.

Could you please tell me who Tony Visser is and also which mudgard you bought?

Thanks

Ian

Tonny Visser makes and sells stainless mudguard brackets for wings that turn with the wheels. He had them advertised on ebay for a while and they are all made to order depending on your wheels, tyre profile/shape and wing. I can't remember exactly which ones I bought as it was about 9months ago. They're probably a little short for most people as they don't really do much more other than being legal.

Depending on your adaptor design the measurement below is probably different to mine.

Thanks again, they look great. Unfortunately I can't find Tony Visser anywhere on Ebay or Google.

I'll have a look at modifying my brackets although I really didn't want to have to cut them.

You don't by any chance have contact details for Mr Visser do you?

Cheers

Ian

It's ok, I've found an email address, fingers crossed

Ian

Sent you a private message.

There is a method to the madness for the original tyre choice!

The 2cv tyres have a rolling diameter of 616mm, which (after a spot of light googling) is exactly the same as the CST 325-17 tyres, meaning the gearing (and therefore speedo reading) was completely unaffected.

Assuming you have a standard late 2cv disc brake gearbox, with the new tyres (rolling diameter of 652mm), you would see the following speeds at 5k rpm

1st 17.8mph
2nd 34.9mph
3rd 51.9mph
4th 70.4mph

Previously, with the CST tyres you would see the following speeds at 5k rpm

1st 16.8mph
2nd 32.9mph
3rd 49.0mph
4th 66.5mph

For my next build I have a slightly taller Ami gearbox and 19" wheels and tyres, which gives 74.9mph at 5k rpm.

Thanks for the info'

Yes I do have the the later twin disc gearbox, I was wondering how much the new tyres would throw the speedo out, I'll check that with my GPS once I get back on the road.

I've ordered my mudguards and sent the info to Mr Visser, hopefully he'll come back with something soon.

Cheers