The setup ground rule for both surfaces: which tyre pressure, spring stiffness and ride height actually deliver time on gravel and on tarmac.
There is one setup ground rule in rallying and it fits into a sentence: the harder and grippier the surface, the stiffer the car may be — the rougher and more slippery it is, the softer it has to become [2]. Everything else is detail.
In numbers: gravel runs the lowest pressures, sometimes down to around 15 to 20 PSI, with softer suspension and more ride height so the tyre deforms, finds the firm base under the loose layer and absorbs the hits [1]. Tarmac runs around 30 to 35 PSI, lower and stiffer, so the contact patch stays stable and the car changes direction instantly [1].
Something you can feel: a gravel tyre at 15 PSI gives noticeably under your thumb — roughly like a football that is half deflated. That is exactly the job: give way, lie into the surface, bite. A tarmac tyre at 33 PSI feels taut by comparison and holds its shape under load.
So the classic beginner mistake is always the same: too much pressure on gravel. The car skips across the surface instead of working into it and loses grip precisely where you need it [1].
Before you turn a single bolt, answer three questions: how grippy is the surface, how rough is it, and how much does it change within the stage? That gives you the direction — grippy and smooth means stiff and low, loose and rough means soft and high [2].
On gravel, go down to the level your tyre and class allow, sometimes around 15 to 20 PSI; on tarmac, up to around 30 to 35 PSI [1]. Always measure cold and write it down. Pressure rises with heat as you drive, and if you do not account for that you finish the stage in a different car from the one you started in.
On gravel the car needs travel: a softer set-up and more ride height so the hits land in the suspension and not in the floor [1][2]. On tarmac the opposite applies: lower and stiffer for less roll and faster direction changes [1]. Run gravel springs on tarmac and you fight your own car for the whole stage.
The rule that separates professionals from beginners: change only one parameter, then drive the same section again. Two changes at once produce a feeling but no knowledge. Note pressure, springs, ride height and weather every time — and what the car did differently.
What you may change is decided by the class you entered [3]. Tyre approvals, suspension modifications and ride height are regulated, and scrutineering checks them. A perfect setup that gets you excluded is not a setup.
Setup is a safety topic, not just a stopwatch topic. Pressure that is too low can unseat the tyre from the rim; pressure that is too high makes the car skip and turn unpredictable on gravel [1]. So stay inside the ranges the tyre manufacturer and the regulations define, and test changes on closed ground, never on a public road.
A clear boundary: safety-critical components are not a tuning field. Roll cage, bucket seats, harnesses and extinguisher system follow the governing body's standards, are fitted by a specialist shop and are checked at scrutineering [4]. Anyone trying to save weight there has misunderstood the sport.
And as always: this guide explains and motivates — it never replaces scrutineering, your national body's regulations or certified driver and safety training.
Establish a reference section: one and the same piece of road that you drive in the same order at every test. Do not just measure the time there — write one sentence about what changed: "front turns in earlier, rear gets nervous". Time alone tells you whether it was better; the sentence tells you why. After three test days you own a setup notebook worth more than any recommendation from the internet.
Gravel runs the lowest pressures — sometimes down to around 15 to 20 PSI — so the tyre deforms, finds the firm base and absorbs the hits [1]. Tarmac runs around 30 to 35 PSI for a stable contact patch [1]. Always measure cold and allow for the pressure rise once the tyres heat up.
By the ground rule: the harder and grippier the surface, the stiffer; the rougher and more slippery, the softer [2]. On gravel that means a soft set-up with more ride height so the hits land in the suspension; on tarmac lower and stiffer for less roll and faster direction changes [1].
The most common technical reason is excessive tyre pressure: the car skips across the loose layer instead of working into it, and loses grip [1]. Check ride height and spring stiffness as well — a car that is too low and too stiff simply never settles on rough ground [2].
Only as a compromise, and it costs you on both sides. The demands run in opposite directions: low pressure, soft and high for gravel against high pressure, stiff and low for tarmac [1][2]. If you run both surfaces regularly, separate tyre sets and a documented setup per surface are the cheaper solution.
Time Card and Time Controls: How to Lose a Rally Without a Single Driving Mistake