MX Nitro: Unleashed

You will not be able to unlock this until later on in the game. To get this achievement you need to fully upgrade the Beast bike which is the 4th one you unlock. This is the only bike that you are able to fully max it the max speed on.

I wasn't able to unlock the final couple upgrades until after I had completed the North America Tour Part 2 and European Tour East sections in career. The final upgrade cost $60,000 so you may need to go win some races to collect enough cash.

For the achievement the quickest and easiest track to do this is the Evening Quay drag race in Mexican Madness. Just simply start off doing your wheelie trick of choice ( or ) until you have a full nitro and then hold to release it. You should hit 189km\h.