I'd been thinking the woman's hat, all by itself, dated this image to 1928-30 rather than 1921. Eventually I realized, confirming this, that the skyscraper in the distance was 1201 California Street, completed in 1930, seen from the southwest. The pic's location is probably smack in the middle of the Western Addition, largely cleared for housing projects starting in the 1950s. Possibly the address was 1150 Webster Street.

The Racine Auto Tire Co. (name also seen on tire) of Racine, Wisconsin used the brand name "Horse Shoe Tire", which corresponded to its signature tread pattern. Here is a 1919 ad.

Shiny shoes aside, the man doesn't appear much concerned with his appearance if the press of his suit is any indication. The car, while a premium make, also bears the mark of benign neglect.

The woman, on the other hand, is very, very Nob Hill indeed. Perhaps her perpetually-between-jobs brother is visiting and she's condescended to go for a ride with him.

The outdoor poster billboard in the photograph was one of many maintained by the firm of Foster and Kleiser, begun in 1901 and transformed eventually into the Clear Channel Outdoor Advertising Company.

Two short chronologies:

http://notablekleisers.blogspot.com/2007/08/foster-and-kleiser-outdoor-b...

http://company.clearchanneloutdoor.com/our-history/

In the mid-1920s, Foster and Kleiser published an extensive analysis of the Pacific Coast advertising market. Their detailed study, complete was billboard samples, is:

https://babel.hathitrust.org/cgi/pt?id=mdp.39015041908370;view=1up;seq=1

Digital images of their billboards are in the:

http://library.duke.edu/digitalcollections/oaaaslidelibrary_SLA1847/

I found two mentions of the dinnerware advert - both behind a paywall. But the ad text reads as follows:

Light up her eye? with a wonderful surprise ! 'Make this Mother's Day really memorable by gifting Mom with something she's always wanted . . . but never really expected . . . a set of new dinnerware ! Remember- "Old dinnerware is a habit - new dinnerware is a joy "

The phrase appeared in both a 1929 newspaper and a 1956 newspaper, so the advertising campaign was rather long-lived.

I wonder how many Moms throughout the years displayed their 'joy' by chucking the old dinnerware at Dad for being so chauvinistic?

The muddy back wheel says "Horse Shoe Cord Tire" on its sidewall. I get it that the tire is to the wheel as the shoe is to a horse's foot, but why that would be an appealing way to market a car product does not seem to translate well today.

As for the habit/joy -- what about his cigar?

[The answer, as noted by the commenters below, is Dinnerware. -Dave]

Dinnerware?

"Old dinnerware is a habit. New dinnerware is a joy."