for me 24-25psi cold (was measured in the summer) is fine for road use. To be honest I prefer how the car drives on the roads in these pressures. Its a little bit more compliant on the bumpy roads.
Setting track tyre pressures is delightfully simple.
Go out and do as many hard laps as you can, come in hot. Set tyre pressures to OEM recommended settings.
That’s it. You’re either exactly at the correct temp or within a few degrees of it.
If you’re miles away from that then question, well question something, your sanity etc.
Note: That is the tyre temp for that tyre, at that track at that ambient temperature.
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On the assumption that OEM pressures are supposed to be cold, a manufacturer will build in the understanding that at motorway speeds, the pressure will increase slightly, and this is also normal. Eg my mx5 will measure 32 psi after a motorway run.
That being the case, and the car being designed for maybe 2-3 psi more when hot, I’ve never quite understood the rationale for running track pressures at the bottom of that range.
At lower pressures the tyre will have more flex, more sidewall movement etc. which will eventually damage the tyre.
I tend to go out at cold pressure (29 for NC) and run a few laps. Usually it ends up about 33-34psi, so I tend to back that down to 30/31 depending on conditions, and that’s where I leave it.
Cold pressure is just that…. Cold. At full hot, I prefer a tiny little bit more in the tyre. Especially on road tyres that have softer sidewalls, they benefit from a little extra pressure in my experience.
I’ve run the Mx5 this year at knockhill, blyton and croft. On Pirelli P Zero, lots of fairly long (15-20 min) fairly hard sessions and at 31psi, the tyres still look good as new.
But as ever, this is just my experience and preferences. I’ve been tracking my cars for about a decade now, everything from
Caterhams to Porsche’s, and I’ve driven most tracks in the UK.
I’ve yet to have this approach to tyre management see me wrong.
with road tyres I stick to 15 minute stints on track and I make sure I don’t overheat the tyres - track tyre pressures are different. Depending on the track and road temperature I think I have achieved 32 psi once at Donnington this summer - I don’t think I’m ever going to get a tyre that hot by driving on the motorway.
28 psi while you are using the tyre is a guideline that seems to work for me (on track) and I don’t seem to burn/bubble the tyre carcass.
Because of the suspension on my car end up having the tyres at 24-25psi for driving on the road and for me is ok. The tyre seems ok, no real degradation but it may not suit others
Cold tyre pressures are not ‘just that’, far from it.
How can it be when it doesn’t have a number or any parameters.
Because the manual states to check pressures when the tyres are cold. Hence, cold pressure.
They don’t say “drive it for three hours, get it nice and hot, and then take the pressure reading”
You know what, having a ■■■■ day and don’t have time or the stress management techniques for Internet know it alls, with no grace for stating their point as “opinion” but instead presenting it as fact.
You do you dude, but try not to engage in conversations where I’m involved huh.
Not the first time you’ve rubbed forum members up the wrong way. Maybe you should think about what that says about you.
If you were both in a pub sharing a pint or two you would get on like a house on fire.
I’ve just read the whole thread and if I was looking for an answer here I’d be at a loss. Not a criticism of the contributors, who I credit with giving honest views and experience.
I suspect there isn’t a one-size-fits-all solution.
Question for NickD perhaps, would the answer be different if using XL tyres as many do?
One thing does concern me. The recommended cold pressure for an MX-5 is 26psi (NA&NB) or 29psi (NC&ND). The normal running pressure therefore will be maybe 1or 2 psi higher.
e.g. if cold pressure set at 17C is 29 psi, and after a drive the tyre is feels warm to the hand (say 37C+) then the tyre pressure will be c. 32 psi**. That’s about 1 psi for each 7 degrees temperature increase.
So if I am happy on a recreational run at 32psi, why would I reset my hot tyres to 29 psi (or less) before stressing them on a track? I would not take that risk.
Mazda does not give a ‘high load’ recommendation for tyre pressure. With 2 up, the MX-5 has a very modest payload capacity, so perhaps it doesn’t need one. But who can deny that the tyres are significantly more loaded on a track than in normal use?
This is a pure thought experiment, and as an armchair expert I’m not going to make any recommendation that isn’t in the manual. What I will say is that at my own modest track speeds I feel very secure with the cold pressures on my 1.5 ND set at 30. FWIW they are the original Yokohama Advan Sport V105.
Picture because I like it.
**Gay Lussac’s law if anybody wants to work it out. For a fixed volume of gas, pressure is proportionate to Kelvin temperature. Just remember to use absolute pressure as well as temperature i.e. 2 bar is actually 3 bar with the addition of ambient pressure. E&OE, I’m not a physicist. I’m assuming there is negligible change in the volume of the tyre when it heats up.
NC 2.0 with Yokohama AD08 205/45/16
I use 32psi HOT, then I may decrease, increase slightly from there
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