Sam Hayes
Number 2 Mechanic at Garage 59, the GT World Challenge Europe team, on their McLaren 720S GT3 EVO Pro car — car number 59 — and co-founder of GripCalc. The advice on this site comes from someone who spends his season preparing a GT3 car for one of the most competitive championships in the world, and who has had every component of a racing car in his hands, most of them more than once.
Garage 59, GT World Challenge Europe
Garage 59 is a multiple championship-winning British motor racing team, launched in 2016 and owned by Alexander West, Andrew Kirkaldy and Chris Goodwin, operating from a Technical Centre in Motorsport Valley. It runs the McLaren GT3 EVO in the FIA World Endurance Championship and GT World Challenge, and manages the race, track and road car collections of private individuals — among them one of the most prestigious collections in the world.
In the summer of 2025 the McLaren carrying number 59 took the marque's first outright Sprint Cup win in GT World Challenge Europe since 2016, in the hands of Marvin Kirchhöfer and Benji Goethe, and repeated it at the following round at Magny-Cours. That is the car Sam prepares, and the standard of preparation he works to every week. It is also the reason a free tyre pressure calculator carries the caution it does about which numbers are published and which are estimated: at that level nobody guesses, and nobody pretends an estimate is a measurement.
Sam is responsible for the preparation, maintenance and performance of that car: full race car preparation, setup changes, component servicing and lifing, fault diagnosis, pit stop operations and rapid turnaround between sessions. It is an environment where precision and reliability are not ambitions but entry requirements, and where the time between a session ending and the car going back out is measured rather than estimated.
Mid-season, he re-tubbed an entire car in two weeks, and it went back out with the pace of a winning car. Anyone who has re-tubbed a car knows what that fortnight looks like, and what it means that the car came good again at the end of it.
Before that, and alongside it
At Datum, all three race cars came down to bare chassis every year and went back together nut and bolt — the whole rebuild, all three cars, done by Sam himself. It is the job that teaches you what each part is for, because you have held all of them and put every one of them back.
He rebuilds Quaife sequential gearboxes himself rather than sending them out, and at 150Motorsport a customer drove over from the Netherlands to leave his car with Sam for a full restoration with the engine and gearbox rebuilt.
Why that matters for pressures
Tyre pressure is where a car's setup meets the road, and reading it properly means knowing what the rest of the car is doing to the tyre: how weight moves, what the geometry does under load, what a tyre's temperatures across the tread are actually telling you. That knowledge is the reason this calculator declares where every number came from instead of presenting one confident figure. A mechanic knows the difference between a manufacturer's published pressure and an educated estimate, and refuses to let a screen blur the two.
So the work here is checkable rather than asserted: the method is published in full, the 27 manufacturer and series pressure sets are carried verbatim and verified against their sources by the engine's test suite on every change, and the circuit figures are measured from mapped geometry with each page naming what was measured and what was estimated. Sam writes the method, curates the open database, and maintains the pressure sheets for 45 circuits, along with the track day pressure guide and the grip force and contact patch tools.
Every number on this site is labelled with where it came from: manufacturer and series figures carried verbatim, estimates declared as estimates. Where something is wrong or a published figure is missing, the fastest way to fix it for everyone is to say so — the database is open and corrections are credited.