A druid's Wild Shape feature specifies the following:
• Your game statistics are replaced by the statistics of
the beast, [bla-fu about stuff you retain; resistances are not mentioned][…]
• You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. However, you can’t use any of your special senses, such as darkvision, unless your new form also has that sense.
Clearly, your resistances are part of your "game statistics". However, they are also clearly a "benefit from your […] race", and not a special sense.
Logically, it doesn't make a whole lot of sense to me why a wildshaped tiefling, for instance, would retain his fire resistance in wildshaped form.
Is someone able to clarify whether or not you retain your racial* resistances while wildshaped?
*I don't care about class-given resistances. It makes a lot more sense for a raging barbarian or a level 17 war domain cleric to keep his resistances than the racial example given above.
Best Answer
RAW and RAT (rules as tweeted), yes, resistances are kept by a wildshaped Tiefling or similar
By using the answers to this question, it can be seen that any and all features that do not explicitly require a feature on the beast (such as Hellish Rebuke requiring a finger to point) are valid for transference.
There may also be circumstances where the feature does not explicitly say whether it requires a physical, racial feature, in which case common sense or DMs ruling may come into play.
In the case of Hellish Resistance, I will outline the example here (this is the full text for the trait):
Nowhere in this statement does it specify that this is due to the player being a Tiefling. This trait, lore-wise, could be due either to the blood in their veins or a boon on their spirit. Either way is outside of RAW, so cannot be discussed.
I would rule, personally, that such resistances are part of a creature's statistics, but that is not RAW. Obviously you can rule as you wish.