1) Tiidde is pronounced as the International Phonetic Alphabet sequence /ti:d:e/, which consists of

(unvoiced alveolar plosive t)
(close front unrounded vowel i of long duration)
(voiced alveolar plosive d with gemination)
(close-mid front unrounded vowel e)

2) Tiid can refer to I) the temporal dimension, "flow", II) a single coordinate or range thereof along the temporal dimension, "moment". In the plural, II is the more likely meaning, though this is not shown explicitly in canon material.

Tiid seems to be able to reference any concept related to the passing of time. Since runners' times would be a measurement of time, and the phrase "good times" refers to a time that was better than the current time, both could easily be described by using the word tiidde.

As for pronounciation, pluralization adds a syllable to the end, and the accent is always on the end for plurals, and they -e suffix makes a sound like -ay. So it would be like teed-DAY.