LOL well it's only common knowledge to us females that when a guy says anything about size and how to use it correctly, its only because they actually really are lacking in the skills to use it correctly.
The smaller the gear the less it gets used, the larger the gear the less it gets used but if it's just the right size then it's just right for all conditions.
So why worry about your 19!! and you should be realistic and learn how to use your 12 or 10 correctly first

.
Also you must remember to inflate it hard, no one likes to see a floppy 12 or 10

XX angie