I'm considering swapping the alloys for steel wheels this winter after I bust two alloys £300 last year, and fitting winter tyres.

I understand that I can't swap 15" alloys for 15" steels without affecting the speedo or something.

I don't really understand this, can somebody explain in layman's terms what I need to do?

Ta,

Dan

It's not just the size of the wheel that's important - it's the combination of wheel, tyre size & profile.

The circumference of the tyre ideally needs to be within 2.5% of what it is now. Use this calculator to work out what you can have.

I use 195/45/R16 tyres on my 16" alloys then 195/50/R15 winter tyres on my 15" steel wheels which is -1.01% different. According to the calculator Speedo reads 70mph your actual speed will be 69.29 mph

That speedo link took me to an altogether unexpected destination!

Edit: it no longer appears as a link, ignore this post.

Thanks, so I do I need to keep the 195 the same, potentially get 14" steels and then try get as close as poss to 2.5%?

Thanks, so I do I need to keep the 195 the same, potentially get 14" steels and then try get as close as poss to 2.5%?

No, you don't need to keep the 195 part the same. You can use 175/65/R14, 185/55/R15 etc... both of those are within 1%.

i must be useless lo, i just have car to get from A to B

If I wanted to keep my current 17 inch alloys on with winter tyres mounted could I use another size other than 205 17 40 if necessary? Maybe 215 17 45?

A quick read up online shows some Bridestones LM's and Pirelli Sottozeros are available 205 17 40 but there are far more options with the 215,45 profile.