I would suggest you just get a 30,
The grim tim's are way slimmer than the new stardards and will stretch about 1-1.5" inch at the waist.
The new standards are known for stretching, people are recommended to size down 2 sizes from your true size.
And even sometimes 3 sizes when worn properly, but be careful of crotch rips if you size down too much...
New standards are going to be hard to put on in the beginning, and about the first 7 wears.
Hope this helps