Not ideal but still fine, as long as the type/level of tires are comparable. For example like me, I currently use Continental Extreme Contact Sport at front and CSC3 at rear, both are UHP category. Or last time on my wife's car V12E2 front and PS4 rear. Better not mix different categories for example UHP and mid range/economy tires coz it might alter the handling noticeably becoming more understeer/oversteer.