A539 tyre pressures

[DaveGr]

 

Done a search but can't find anything on tyre pressures for Yoko 539's. Had them fitted to my vx classic 8v a while ago and found this am that they are running at 30psi cold. Is that high? What is right for normal road use and what should I use at the cadwell track day?

 

Grateful for any advice,

 

Dave

[Allen Payne]

I would have thought nearer 20 than 30. For the road, admittedly on different tyres, I only use 18psi.

 

Edited by - Allen Payne on 29 Apr 2006 14:12:08

[Fathead]

I run A539s on 20psi, originally had them at 25 when i got the car.... still haven't worn out 8k later. Bringing the pressure down really improved things

 

Tom The most southerly uk blatter

😬Yellow 1.6 Supersport 😬 Photos here

[JonathanP]

I run mine on 19psi warm, I would have thought much over 20 would be too high for a 7.

 

Jonathan

 

[Brucey]

Dave,

 

I have 185/60/14 A539 tyres fitted to my 7. I run them at 20 psi (cold), which seems fine.

I'd say 30 psi is way too high for the weight of the car. Let them down a bit and try it as things like tyre pressures have a huge impact on handling and comfort on a 7.

 

When I bought my car the previous owner had pumped the 205/45/16 tyres up to 50psi (probably for winter storage) and forgot to let them down. I found myself 'clenching my buttocks' every time I drove over a cats eye! I let them down to 18 psi and totaly transformed the car!

 

Bruce.

[SvenDriver]

I run mine at 19psi. I found that 16-18 tended to judder slide and 20 tended to loose grip a little too fast.

[DaveGr]

 

Thanks everyone - had no idea that they were running at thirty as they were fitted in my absence, but i shouldn't have assumed they were okay. I was running some very worn cr322's before and had been told that the 539s would transform the car, which they didn't really. I realise why now!

 

Thanks

dave

 

[susser]

Based on the simple physics that Pressure is Force per unit of area. It follows that a tyre at 30 psi will have a contact area of 60% of one at 18 psi.

QED.

Don't get carried away and think that if you drop the pressure to 5 psi you'll get 6 times the grip *idea*'cos you won't.

[Peter Carmichael]

Based on the simple physics

 

... but poor analysis.

 

The road surface is not the only thing restraining the force exterted by the pressure. The carcass of the tyre restrains the force too. While the principle of less pressure is correct, the reason is partly also to have less preload in the sidewalls of the tyre. The tyre works by "standing on its sidewalls", not merely by being an air bag.