"These shoes are much prettier than yours."

Translation: Ces chaussures sont beaucoup plus jolies que les tiennes.

[dmidye]

Why not 'chaussures-ci' here?

[Sitesurf]

The suffixes "-ci" and "-là" are mostly used together in full comparisons like, "Ces chaussures-ci sont beaucoup plus jolies que ces bottes-là".
In this sentence, the comparison is explicit enough with "ces" and "les tiennes".

[DanielPers200180]

Way prettier is correct here?

[KelvinJackson7]

Can 'tien/tiennes' also be used in formal situations?

[PATRICKPIZ1]

if you vouvoyer the person you are speaking to you have to use 'le vôtre', 'la vôtre' or 'les vôtres'. (note the accent, these are pronouns)

if you tutoyer them you use la tienne, le tien, les tiennes, les tiens.

[Bugeau2]

Ses chaussures (à elle) ou ces chaussures (ci) ?