will i have more flat tires with the low profile tires
You probably won't have any flats at all.
Yes you will. Unless you plan to do a lot of high speed cornering. I don't think they are needed.
You are more likely to have a flat tire with the low profile tires. Let me give you an example that may help, if you run into a curb while parking, the low profile tires are more susceptible to flats than the regular tires. This doesn't mean they always get a flat, just more likely. And remember, all tires can get flats.
Flats are not really the issue. Increased chance of rim damage is the real risk, which may or may not lead to a flat. I am not too worried about destroying my 21" rims driving in California, but I'd be very concerned driving through the numerous springtime potholes in Illinois.
Rim rash is the main problem with 21" tires, it drives me crazy. I have a local guy that fixes them but it is still ulcerating when you here the sound of your rims being eaten up by a small curb.
I make a point of not running into a curb when driving a $100,000 car. I drive a less expensive car when I don't feel like paying attention to the road hazards around me. The .35 profile 21" wheel/tires should provide great service for any attentive driver.
I had a flat on a small pot hole. I then ordered and replaced them with the 19s. I don't have time for flat tires.
Had one wheel replaced yesterday. 21" Michelin. $670 for the one tire. $870 for labor and taxes. No joke.
+1 bnwdon - with the low profile tires, the rims extend beyond the tire, so brushing up against anything causes rim rash. I've found if I back into a parking space using the tilting mirrors, I have a much better chance of avoiding the curbs (and rim rash) than pulling in forward. Can't see the front right wheel when pulling in forward.
No. The chance of a flat tire is the same. A pucture is a punture regardless of side wall thickness. You can even argue it's harder to get unrepairable sidewall puncure on low profile tires. However there is better chance that you'll get a bent rim if you hit a pot hole hard when there is less sidewall to absorbe the shock.