I only ride in the city so want to replace my tires with something more appropriate, I can’t decide on a width ranging from 1.75 to 2.125. I like the look of a whitewall but those seem to only be available in 2.125 beach cruiser are those ok? Also should I get new inner tubes?

Neither of those rules are strictly true, and they're very often not true at all. Tire rolling resistance is mostly a product of sidewall construction and rubber compound. For example, compare the popular WTB Byway with a slick center tread and the Continental Race King MTB tire with knobs -- the MTB tire with knobs is about 50% faster.

Also, when comparing two tires of identical construction and differing only in width, the wider one will have less rolling resistance at the same pressure.

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