Recently bought an 06 Octavia 1.9 tdi estate, it is fitted with 205/60/15 but on the fuel filler flap when checking for tyre pressures it also states tyre sizes, 195/55/15, 195/65/15, can any of these sizes be used on same axle or will speedo read way out

thanks

I think 205/55 R 16 is the default size (for my OE spare anyway). Your tyres are negligibly smaller, and you won't notice the already overreading speedo - you'll get a marginally better safety margin compared to true speed.

The 195/65 R 15 halves that negligible discrepancy from default if you can indeed fit 15" wheels.

195/65 R15

205/55 R16

215/45 R17

195/65 R15

205/55 R16

215/45 R17

225/40/18

15" rims won't clear the standard calipers with 288mm or larger discs; not sure about on the Octy 2, but on other Skoda models the 288mm discs will be associated with DS3 calipers, and 280mm or smaller with FS111 calipers.

More generally, tyre sidewall height is giver by tread width, say 205mm * aspect ratio, say 60, divided by 100, for 123mm. To get an overall rolling radius, add half the wheel size, say 16, re-expressed in mm. For 16" wheels, this is 8*25.4, or 203.2. Giving you a rolling radius of 326.2mm (ignoring tyre wear).

Fitting 55 ratio tyres, leaving everything else constant, reduces wall height to 112.75 mm.