Hi all

I am thinking of going down to a 19" wheel from a 20" for a more comfortable ride. I know that its possible to get the speedo changed by the dealer, but does anyone know what the difference in the speedo reading would be if I left it unaltered until I can get booked in?

Cheers Roy 2005 L322 Vogue Gold gone
2006 L322 Vogue Black gone
2011 L322 Vogue Silver gone
2011 L322 Autobiography Black gone
2015 L405 Autobiography LWB Black gone
2019 L405 P400e Range Rover Autobiography LWB Eiger grey / black roof gone
2001 P38a 30th Anniversary Wimbledon Green gone
2019 L405 P525 Autobiography LWB British Racing Green

It's the tyres that matter

There are loads of online convertors that will give you the % difference

If you fit the standard tyres that LR fit to 19" wheels, then they should be very close and no further adjustment needed

255/55/19 are the same diameter as 255/50/20

They are official LR, so that should be OK then, cheers! 2005 L322 Vogue Gold gone
2006 L322 Vogue Black gone
2011 L322 Vogue Silver gone
2011 L322 Autobiography Black gone
2015 L405 Autobiography LWB Black gone
2019 L405 P400e Range Rover Autobiography LWB Eiger grey / black roof gone
2001 P38a 30th Anniversary Wimbledon Green gone
2019 L405 P525 Autobiography LWB British Racing Green

If you run stock size tyres on 19" & 20" they will be the same .

255/55-19 are the same as 255/50-20 & 255/60-18

The 19's are 0.004" bigger than the 20's, and I'm not even going to bother trying to work out how much faster you'll go on an extra 4 thou, it will be a fraction of a mile an hour when your flat out. The speedo's read slightly over, so there is no way you'll set a camera off, providing you stick to the speed limit
My car is doing 69 mph when it reads 70 mph on the speedo, if your that worried about it, find someone with an after market sat nav that shows the speed your traveling at and check it against the speedo. If you cant find someone with a sat nav then I'd suggest that you consider buying one, as it will be a heck of a lot cheaper than having your speedo calibrated  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Here's some interesting reading for you

http://www.thecarexpert.co.uk/how-accurate-is-a-car-speedometer/ Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

From an online tyre calculator

http://www.1010tires.com/Tools/Tire-Size-C.../255-60R18

If we use 255/60-18 as stock = 62.14 mph

255/50-20 = 62.12 mph - 0.03%

& 255/55-19 = 62.13 mph - 0.01%

If you can tell the difference of 0.02 mph your a far better man than I

Gary