How does IUPAC name TRICARBOXYLIC acids?

1) If there are multiple carboxyl groups on the same parent chain, the suffix "-carboxylic acid" can be used (as -dicarboxylic acid, -tricarboxylic acid, etc.). In these cases, the carbon in the carboxyl group does not count as being part of the main alkane chain. The same is true for the prefix form, "carboxyl-". Citric acid is one example; it is named 2-hydroxypropane- 1,2,3-tricarboxylic acid, rather than 3-carboxy, 3-hydroxypentanedioic acid.

2) The suffixes -diol, -triol, -tetraol, etc., are used for multiple -OH groups: Ethylene glycol CH2OHCH2OH is ethane-1,2-diol.

I agree with you as we know that the IUPAC system especially in giving name for the hydrocarbon the first we must consider is the alkyl group and stating it by the alphabetical order

they have long stories!a book is released about this.but i hope this help you:
http://www.chem.qmul.ac.uk/iupac/