Loading page
About this tool
Check monsoon readiness: wet stopping distance from tread depth, aquaplaning speed from tyre pressure and a weighted pre-rain checklist.
A monsoon driving readiness checker turns two measurements — tread depth and cold tyre pressure — into the numbers that decide a wet-weather stop. Braking distance is computed as v²/(2μg) with a wet friction coefficient chosen from your tread depth, reaction distance uses a 1.5-second wet reaction time, and the aquaplaning onset speed comes from the NASA rotating-tyre formula V = 9√p knots (Horne & Dreher, TN D-2056). A weighted eighteen-point checklist covers everything a gauge cannot measure.
Open Monsoon Driving Readiness Checker on AltFTool — it loads instantly in your browser.
Measure and enter Tread depth (mm), Cold tyre pressure (psi) and the speed you actually cruise at (km/h).
Tick the weighted checklist grouped under Tyres & brakes, Visibility, Sealing & electricals and Documents & kit.
Read Stopping distance in rain with its verdict, plus aquaplaning onset speed, rain following gap and checklist points; press Copy result.
Reports the actual extra metres your worn tread costs at your cruising speed.
Uses the published NASA formula rather than a generic 'slow down in rain'.
A dead wiper or an untested brake stops the checklist instead of costing a few points.
1.6 mm in the principal grooves for passenger cars, set by Rule 94 of the Central Motor Vehicles Rules. That is a legal floor, not a safe one — wet grip falls away below about 3 mm, which is where most tyre makers advise replacement before a monsoon.
For a rotating tyre the onset speed in knots is roughly nine times the square root of the inflation pressure in psi, so about 94 km/h at 32 psi and only about 85 km/h at 26 psi. Because the speed scales with the square root of pressure, an under-inflated tyre starts floating noticeably earlier — which is why weekly cold pressure checks matter more in the rains.
Typically 50% to 70% longer than on dry tarmac at the same speed. From 80 km/h a car with healthy tread needs roughly 54 m dry and about 84 m wet, because the friction coefficient drops from around 0.8 to 0.5 and rain adds about half a second to reaction time.
No. Hazard lights disable or mask your indicators on most cars, so nobody can tell when you are about to change lane or turn, and a stationary-hazard signal on a moving car confuses everyone behind you. Use headlights on low beam, or fog lamps if fitted, and slow down instead.