Tyresome...

[JetSepter]

Yes, yet more about tyres.  Thought I would share with anyone who wants to know, that Yoko AD09Rs, which only come in 50 rather than the CR500's 45 profile, are just that smidge too big to fit clear of the front cycle wings and stays that Caterham use for CR500 195/45/15s. (At least those on my 2011 car.) I am hoping to get my local garage to weld in some short extensions to the four stay tubes, though I guess there will also have to be a bit of realigning to match everything up. Hopefully the cost of this little job will not eat up too much of the saving the Yokos represented over a set of Avon ZZSs.

[Wrightpayne]

Are the wings bolted or bonded? When you extend the tubes the fixing points will change.

[JetSepter]

Indeed. That was the realignment I was referring to. The wings are bonded. Rather than unbond them, I am expecting to bend the forward (more upright) stay (once cut and with its extension) to match up with the new position of the part of the stay remaining attached to the wing. There may be pictures in my blog if I get it right.

[SLR No.77]

You might struggle to have welding done on the stays without removing the wings and re-bonding later. Better to remove them and have the welding done in the area that is hidden by the wings when you refit later.

Stu.

[SM25T]

Always remove the wings before doing anything to the stays.

[JetSepter]

The deed is did. Front stays have been extended with some inserts and sleeves, and their geometry changed slightly through some rewelding. You can just about discern one of the joins, but you'd be hard put to it to spot the rest. An excellent job by Darcy Watts at Perranwell Classic Cars. Oh, and the Yokos now fit neatly under the cycle wings. I'll try and pop up some photos on my blog in the next few days. Meanwhile, I need to take advantage of the new tyres and the sunshine we have today down yer in deepest Cornwall.

[Jonathan Kay]

Well done.

Did you remove the wings from the stays?

Jonathan

[JetSepter]

Jonathan - here's a delayed reply!!!  No. As you know the wings are sikaflexed on. They stayed that way. Guess Darcy did some rather careful welding.

[Jonathan Kay]

: - )

Thanks

Jonathan

[Reindeer]

In the end I decided to stay with my 15 inch wheels for now....

So I bought the Toyo TR1s in the correct CR500 size.

I've been very very impressed with them so far....recommended!

(I run them at 18 psi)

[supersport_140]

I am running Toyo TR1 195/45 R 15

Oakmere put 28 psi in them. I was wondering what pressures others were running.

[SM25T]

28psi 🫣 .... try 18 cold

[Golf Juliet Tango]

28psi - oh wow! An odd pressure, you need a bit more to seat the beads but much less if you ard driving the car.

[Golf Juliet Tango]

Yes, 18 is a good starting point.

[supersport_140]

I am beginning to doubt myself. I will double check and drop the to 18psi.

[StevehS3]

For years I ran 18 PSI for road. Now I wonder if that was low because they never get properly hot on the road. I ran 26/24 PSI on ZZS at Anglesey in the [very] wet and it felt great. Admittedly different tyres but this is from Avon.

 

[OldAndrewE]

2 minutes ago, StevehS3 said:

Now I wonder if that was low because they never get properly hot on the road.

All other things being equal (speed, cornering) wouldn't lower pressure tyres get hotter because of the greater sidewall flexing?

[StevehS3]

49 minutes ago, OldAndrewE said:

All other things being equal (speed, cornering) wouldn't lower pressure tyres get hotter because of the greater sidewall flexing?

Possibly but I don’t think it will ever happen on the road. Track is completely different. 

[David aka Blue7]

On 04/09/2024 at 20:03, supersport_140 said:

I am running Toyo TR1 195/45 R 15

Oakmere put 28 psi in them. I was wondering what pressures others were running.

Well that came as a surprise to me, I didn't realise that anyone other than Avon produced a 195/45 R15.  It has always been a problem for CSR owners when Avon stopped making them and substituted them with 195/50, some owners managed to squeeze them below the cycle wings and others had to adjust the cycle wings to get them to fit.  I just bought a good stock of CR500 195/45 but it is handy to know Toyo make them.  The big problem now seems to be sourcing the rear  tyres 245/40 but I have just fitted two new and have two more in stock.

As for PSI, 28 is far too high but Garages tend to inflate any new tyres they fit to Caterhams to 25 psi and expect owners to change the pressure to what they desire.  As others have said, I run on 18psi, in my experience, any more than that results in excessive wear down the centre of the tyre.

What is happening with Nova, are they up and running yet?

[Jonathan Kay]

4 minutes ago, David aka Blue7 said:

What is happening with Nova, are they up and running yet?

Jonathan

[Reindeer]

25 minutes ago, David aka Blue7 said:

Well that came as a surprise to me, I didn't realise that anyone other than Avon produced a 195/45 R15.  It has always been a problem for CSR owners when Avon stopped making them and substituted them with 195/50, some owners managed to squeeze them below the cycle wings and others had to adjust the cycle wings to get them to fit.  I just bought a good stock of CR500 195/45 but it is handy to know Toyo make them.  The big problem now seems to be sourcing the rear  tyres 245/40 but I have just fitted two new and have two more in stock.

As for PSI, 28 is far too high but Garages tend to inflate any new tyres they fit to Caterhams to 25 psi and expect owners to change the pressure to what they desire.  As others have said, I run on 18psi, in my experience, any more than that results in excessive wear down the centre of the tyre.

What is happening with Nova, are they up and running yet?

I'm confused.....for the stock 15 wheels that were fitted to the Roadsports....did they fit larger rears?

I thought it was same size all round? 195 45 15?

[David aka Blue7]

13 hours ago, Reindeer said:

I'm confused.....for the stock 15 wheels that were fitted to the Roadsports....did they fit larger rears?

I thought it was same size all round? 195 45 15?

You are correct, sorry for the confusion, I was referring to a CSR that have 245/40 on the rear  and are presently like hens teeth to source

[Nigel B]

Having run my car with the tyres inflated to the regulation 18psi (cold) for the past couple of years, I’m reaching the conclusion that, in my case at least, 18psi is a little too high.

I’m about to fit a new pair of rears & looking at the old pair, they’re down to the tread wear indicators in the centre of the tread, but there’s still some tread remaining towards the edges. Road use only, I haven’t done any track days in that time. 

I’ve experimented with different pressures in the past & I find higher pressures simply reduce the grip level. I’ve never gone anywhere near 28psi, I think that would be pretty hair raising!

[supersport_140]

Thanks guys. Tyres are now down at 20psi I was not brave enough to go all the way to 18psi but it sounds like I should. A quick local run handling felt the same, but I was not really pushing it. And the ride felt less harsh.

 

 

[DanRo]

When I bought a set of 13in wheels 3 years ago, they came with some new Nankang NS2Rs. On then drive home, I thought I’d made a grave error and bought some dangerous tyres. The handling was overly direct and sensitive and the car was bounced around by bumps and over reactive to steering inputs. When I got home, I checked the pressures and they were all at 21psi. I put them down to 18 and the car was cured. I’ve run them on road and track at 18 ever since. I couldn’t believe how little pressure change made such a difference.