In Catholicism, what are some examples of views considered opinio tolerata?

One example would be that of Limbo. Regarded less in this century then in the past, there are refrences to the state of Limbo from the early fathers and the idea has not been completely abolished. I might suggest also the age of the earth itself, Catholics are free to beleive as many Young Earth Creationist do, that the earth is only 7000 years old ish. Regardless of what God has revealed to us about the true age of his creation through science. So the Idea, which most regard as non-sence is a tolerated opinion as it has no bearing on the faith or teachings of the Church.

Theological opinions are the lowest grade of theological notes:

9. Theological Note: Very common/commoner.
   Explanation: The most solidly founded or best attested t͟h͟e͟o͟l͟o͟g͟i͟c͟a͟l͟ ͟o͟p͟i͟n͟i͟o͟n͟ on a disputed subject.
   Example: Antichrist will be of the tribe of Dan.
   Censure attached to contradictory proposition: None.
   Effects of denial: None.
   Remarks: Very common or commoner o͟p͟i͟n͟i͟o͟n͟s can be mistaken and there is no obligation to follow them though prudence inclines us to favour them as a general policy. It should be noted that an o͟p͟i͟n͟i͟o͟n͟ which is "very common" is less well established than one which is "common" which implies moral unanimity of theological schools.
10. Theological Note: Probable.
    Explanation: A t͟h͟e͟o͟l͟o͟g͟i͟c͟a͟l͟ ͟o͟p͟i͟n͟i͟o͟n͟ which is well founded either on the grounds of its intrinsic coherence or the extrinsic weight of authority favouring it.
    Example: Judas received Holy Communion at the Last Supper. Judas did not receive Holy Communion at the Last Supper.
    Censure attached to contradictory proposition: None.
    Effects of denial: None.
    Remarks: The better founded of two conflicting o͟p͟i͟n͟i͟o͟n͟s is referred to as more probable; but Catholics are free to prefer some other o͟p͟i͟n͟i͟o͟n͟ for any good reason.

source: this full list of theological notes, the first of which is dogma (de fide).

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Limbo ranks higher than a mere theological opinion because a pope settled that theological debate (that popes can do this, see: Humani Generis §20).

Pope Pius VI's “Auctorem fidei,” Aug. 28, 1794—reproduced in Denzinger-Schönmetzer, Enchiridion Symbolorum, definitionum et declarationum de rebus fidei et morum. Ed. 34. 1965, §2626—says:

26. The doctrine which rejects as a Pelagian fable, that place of the lower regions (which the faithful generally designate by the name of the limbo of children) in which the souls of those departing with the sole guilt of original sin are punished with the punishment of the condemned, exclusive of the punishment of fire, just as it, by this very fact, that these who remove the punishment of fire introduced that middle place and state free of guilt and of punishment between the kingdom of God and eternal damnation, such as that about which the Pelagians idly talk,—false, rash, injurious to Catholic schools.

Before going into some examples of some tolerated opinions in Catholic theology, it would be beneficial to understand a few terms first.

What is a tolerated opinion in the eyes of Catholic doctrine?

In Catholic theology, opinio tolerata refers to pious beliefs with a low degree of theological certainty, but which are tolerated by the magisterium of the Catholic Church. These are ranked less certain than sententia probabilis and hold the least degree of certainty in the hierarchy of dogmatic teachings for Catholics. - Opinio tolerate (Wikipedia).

What are pious beliefs, or as some call them popular beliefs?

• Did the Annunciation and Good Friday coincide?
• Some Catholics believe that Mary did not see death when she was taken up to heaven. In the Apostolic constitution, Munificentissimus Deus, Pope Pius XII defined the dogma of the Assumption of Mary. However, Pope Pius XII deliberately left open the question of whether Mary died before her Assumption.
• Catholics are free to believe that Mary is the Mediatrix of All Graces since this too is at the present moment an undefined dogma in the Catholic Church.
• Some Believe that Jesus was crucified near the tomb of Adam at Calvary.
• Before 1854, when Pope Pius IX defined the dogma of the Immaculate Conception in his papal bull Ineffabilis Deus, some Catholics were of the opinion that Mary was conceived without sin, while others doubted this privilege as being given to Mary. Once this decree was promulgated on December 8, 1854, Catholics must believe that the Immaculate Conception is dogma.
• Some of the faithful honor Mary with the title of Co-Redemptrix and as of the present moment it has not been defined as Catholic dogma. Catholics are permitted to hold this opinion. Pope Benedict XVI was not in favor of the dogmatization of this subject.

These are just a few of the many piously held opinions of some of the Catholic faithful.