Check the tyre inflation pressure label attached to the driver’s door frame for the correct inflation pressures for your vehicle. There is also a Specifications section in the Owner’s Manual that lists the correct pressures for different CX-3 models and different wheel sizes.
It’s recommended that you check all tyre pressures (including the spare if you have one) every month. Check the pressures when the tyres are cold.
At the time of writing, you can download PDF versions of Owner’s Manuals from the Mazda UK website, here – https://www.mazda.co.uk/owners/videos-and-manuals/
Just select the model and year you’re interested in, using the drop-down menu’s on the page.