Tyre Prices

[Britprius]

25 minutes ago, DaKa said:

Can I add another aspect to this topic.

Having recently sold a spare set of  LS430 17 inch rims refurbished from a 2001 model to someone who preferred them to their perished later 2006 model 18 inch rims.

Before investing in new tyres and potentially spending 400 to 600+ quid, would it be better to convert to 18 inch wheels/tyres from later models first?

Handling, ride, compatibility, speedo accuracy etc.?

A bit of a mix bag of questions there.

Smaller diameter rims with higher aspect ratio tyres will generally give you a more comfortable quieter ride. Handling will become less predictable though as the tyres will flex more under cornering loads. 

Speedo accuracy is affected by the rolling radius of the tyres chosen or TPM figure (turns per mile) not by the rim size. you can check the rolling radius of any given size of tyre with the many calculators found on line. 

Many cars come with different wheel and tyre size options, but you will find all the options produce the same rolling radius TPM of the tyres within a small percentage typically 2%. Speedo's on all production cars over state the speed of the car, and this is allowed for within the law, but it is illegal for a manufacturer to produce a speedo that under reads your speed.

John