Downsizing wheel/tyre combo

[Mizeeks]

Hi all,
I'm currently driving 2012 Lexus GS250 fitted with
235/45 R18 summer tyres.
I've bought a set of alloys 17x7.5 J - please advise optimum tyre size to suit.

[Scrump]

Are there any 17 inch tyre sizes listed on the tyre pressure sticker?

A few possible tyre sizes, for example:
225/50 x 17 would be only very slightly shorter (1.8% speedo error)
235/50 x 17 would be near identical size
225/55 x 17 are only slightly taller (1.7% speedo difference, may actually make the speedo more accurate)

but not sure if any of these sizes are actually available

[vikingaero]

Also look in the handbook for alternative/recommended tyre sizes for the 17" wheels.

[Krikkit]

225/50 would be my choice, but as Scrumpy noted above there would be a slight change in rolling radius (1.8% isn't anything to worry about imho)

235/50 and 225/55 are reasonably available, but 225/50 are a very popular size and hence significantly cheaper.

[Pica-Pica]

Check the car’s tyre label and here
http://www.wheelcalc.com/

[Mizeeks]

Thanks to everyone for your prompt response