Can I use both same 21 inch car wiper blades on the Front wind shield on Civic 2004?

 

no

 

I got the trico force ones 21/19inch from rockauto for about 7 bucks each. They work great and are highly recommended. When I put some wrong sized wipers on that I had lying around they touched the weather stripping. When that happens it lifts up off the windshield. So you can't add even one inch without this happening. I guess you could go a little smaller just not bigger on either wiper.