I'm sorry if I posted the topic in the wrong place.

Do I have to pay to upload higher quality skins ?
I looked at it and it just said you can't upload over 1.5MB and says it will be 1024x1024.

IMAGE REQUIREMENTS :
JPG format (use the .JPG extension)
car skin dimensions, minimum / maximum : 1024*1024 / 2048*2048 pixels
helmet skin dimensions, minimum / maximum : 512*512 / 1024*1024 pixels
the uploaded original may be no bigger than 1.5MB
When you update a skin just re-upload it with the same name. LFS checks the file-date of a skin to decide if people should re-download it.

Tip : you can also drag and drop skins onto the skins overview page.

As of now, 2048x2048 is the max resolution you can upload for car skins.