My 1997 Ford Fiesta MK4 is running on "steely" wheels with the standard 165/70 R13 T "All Season" tyres on, and I was wondering what I should do when the snow comes.

Should I lower the PSi to around 24-25 or something, like I have the last couple of years, or should I increase them to 30-31 PSi ?

When I lowered the PSi the previous winters, the car has spun its wheels and locked up, but I don't know if that is because of the lower PSi or not, so I don't want to do the opposite this winter, and end up having them spinning and locking up even more!

We don't have money for winter tyres by the way.

My 1997 Ford Fiesta MK4 is running on "steely" wheels with the standard 165/70 R13 T "All Season" tyres on, and I was wondering what I should do when the snow comes.

Should I lower the PSi to around 24-25 or something, like I have the last couple of years, or should I increase them to 30-31 PSi ?

When I lowered the PSi the previous winters, the car has spun its wheels and locked up, but I don't know if that is because of the lower PSi or not, so I don't want to do the opposite this winter, and end up having them spinning and locking up even more!

We don't have money for winter tyres by the way.

I think your wheels may be too thin to get proper grip in the snow perhaps a wider tyre on a 15inch wheel would be better even if fitted with all weather tyres or purchase a set of snow socks

Deep snow thinner tyres

He has said can't afford winter tyre so the only option is to change pressure,

Usually wide snow tyres and very low pressures work

Rally cars use very thin nobbly tyres

In this case it's try the pressures and see what works

If the tyres are incorrect fir the weather conditions you will only improve a little bit, the biggest overall improvement will be your driving style, gentle braking and acceleration, gentle turning, looking further ahead