How fast do Krogan's run?

Good question, if we go by me3 MP or the me2 enemies, then krogan are not faster than humans/shepard (drell otoh...)
If we use me1, then krogans are fast enough to always catch you and body slam you through a wall before headbutting any remains into fine dust.

But: Game Krogan are also massively scaled down most of the time, to have the same size as humans!
Using a numbers based approach, assuming that their speed to hight ratio is the same as for humans:

• Humans run <= 10.44 m/s or 37.58 kph (source: de.wikipedia.org/wiki/100-Meter-Lauf)
• Human male average height is about 171 cm (source: en.wikipedia.org/wiki/Human#Biology)
• Krogan height is > 7ft - lets say that means ~240 cm (source: masseffect.fandom.com/wiki/Krogan#Biology)

(Stacking massively in favour of krogans, because they are cool and this way we get an upper limit instead of something that may or may not probably be somewhere in the right vicinity)

Using those numbers and assumptions, an average krogan runs slower than 14.65 m/s or 52.74 kph.
In other words - Wrex does not need the Mako! He only stays because of the cannon

Going up to 52.74 kph lines up very close to the song about 'Commander Shepard" if we take the "You can fight like a Krogan, run like a leopard..." part literal in that the Krogan can run similar to that of leopards in terms of speed which is insane with all that heavy armor they wear.