Tyre pressures

[Mrp]

Simple question My 420 SV runs 15" wheels with the normal Avon ZZS tyres what pressures are people running these at for normal road use.

Think it might be different than my previous S3 on 13"

Thanks

Mrp

[Toughie]

Interesting one, this.

Here's Avon's table on this page with the tyre pressures they recommend.

https://www.avontyres.com/en-gb/tyres/zzs

You'll see they give different pressures depending on the tyre size.  From my Get to Know Your 7 course at Caterham, they usually recommend 18psi (cold) all round.t

Caterham fited a set of ZZS to my CSR when I bought it from them.  My tyres are 245/40R15 on the rear and 195/50R15 on the front.  Caterham said they should be 24psi (CSR's are fat and heavy by 7 standards).

You can see from Avon's chart, however, that they recommend 22psi rear and 30psi front!

So, I've emailed Avon to ask, got a phone call back from a nice bloke called Adam, who is looking into it and has promised to get back to me.

In the meantime, I'm running at 23psi all round, 'cos at 24psi, the ZZR is so tight a fit, it scrapes the leading edge of the CSR front wings.

[David Brown]

Having wear on my previous set in the centre of both front and rear of my CSR on my ZZS at the higher pressures, I have reduced them to 18psi cold. 

[GulfSeven]

I asked Caterham when my 310R was delivered last year and they said 18psi. That's ZZS on 15" wheels.

The approach I took with my Elise was to go with the manufacturers recommendation and maintain that by letting out air after each session on track, so I'll probably do the same with the Seven.

[Toughie]

Right.  Avon have come back to me. 

I had contacted Avon anyway about the service they can provide, so shall post about that in a day or so on a separate thread and on Member Benefits.

What Avon have told me, however, is that for my CSR (fat and heavy), 22 psi (cold) all round would be the ideal.  The reason they state higher pressures on the guide I gave the link to, is that they also provide ZZS for other, heavier sports cars, so the pressures are for them.

Gulfie, yes, as stated, 18psi is what CC usually recommend as per the GTKY7 course, along with letting the pressures out if the heat generated on track takes them over 24psi.  At the time I had an SV Roadsport, not my heavier CSR.

In my notes from the day I've written:-

"18 PSI fine for road.  Track day when hot should be around 24 PSI"

 

[Mrp]

Thanks Toughie, tyres reset to 18 psi

Mrp

[Toughie]

Three things, following on. 

1. Interesting to note that the bloke who ran the Get To Know Your 7 course I attended was Simon Lambert, Caterham's Chief Motorsport & Technical Officer, who starred on our recent webinar with Caterham, shortly to be available online, so I couldn't really ask for a better source.

 

2. If you are testing the pressure and don't have a whizzy bit of kit, I can recommend the RaceX 0014 tyre pressure gauge.  Accurate to within 3%, inexpensive (£11.50) and small, so it doesn't take up much space in your boot.  My predecessor in this role, Geoff Brown, wrote a piece about it in Lowflying, which is what prompted me to buy one.  Here's the link for his article:-

http://lowflying.lotus7.club/2016/2016_06_06_Pressure.pdf

You can get them at Opie Oils, where you can also use the Club's discount, here:-

https://www.lotus7.club/membership/special-offers-members/opie-oils

 

3.  I had my car mapped at Northampton Motorsport after a Caterham did an "engine refresh" for me (which sounded to me more like a full engine rebuild).  Troy at Northampton let me in while he did the Rolling Road run, and I noticed he had a nice thermal imager, so took the opportunity to use it to measure the inner, middle and outer rear tyre temperatures whilst it was on the roller.  As their RR has a single roller, I assume it better reflects the heating you'd get on the real road.

It was really interesting to observe the temperatures change at different points across the thread as the tyre heated up.

[GulfSeven]

Those pressure gauges are a must-have on a track day.

I've got this one: https://www.eliseparts.com/shop/tools/tools/tyre-pressure-gauge-with-flexible-hose/

[Ballast-ic]

DemonTweaks stock the PitKing one that goes from 1-30 PSI, so much easier to get an accurate reading at 18-20 PSI. Most of the other go to 100PSI, so 18 PSI registers as a gnats fart. https://www.demon-tweeks.com/uk/pitking-products-deluxe-tyre-pressure-gauge-336041/. Not the cheapest, but worth a look. Don't forget your 10% discount 

[John Vine]

I've used the RaceX gauge for quite a few years.  All-round excellent bit of kit.  It lives in my SBFS tunnel-top touring bag (also an excellent bit of kit).

JV

[GulfSeven]

#7:

Gulfie

What's this 'Gulfie' thing? You can't just go around abbreviating and adding "ie" 

[opplock]

#11

abbreviating and adding "ie". Must be Australian.   

 

[Toughie]

Oh, aye!  Go down everyone's throats when they're being chummy, and only then do you stick your real name down!

There's a Gulf opening up in this relationship, and I know whose fault it is!

[GulfSeven]

I'm surprised our profiles don't have our first names on them actually to make this sort of thing easier. That's not actually the first time I've put my name on a post... I did sign off Tim on my first ever post too