First Post & First GP since Watkins Glen

I dropped in on the US GP Practice last Friday. Took these shots in the afternoon at Turns 9-10. This is my first post here. Any comments and advice appreciated. Any other advice on how to size images would also be helpful.
Al

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no reply's . im not a motor sport shooter but i think you have used to fast a shutter speed and frozen the weels i think guys pan and use around 1/300 sec to get the weel movment yet still get the car sharp .
to size it wants to be 800 on the longest side i.e in this case the width and 100k max file size .
Rob.

Thanks for your reply and comments. I have not shot motorsports for a long time and I was using a 500mm f4 lens with a 1.4 TC so shooting at 700mm from a tripod in a crowd. It was a bit difficult to pan but the comments will help me do better next time.