Pairameter or Peirameter: How To spell?

The word Pairameter is misspelled against Peirameter, a noun meaning "A dynamometer for measuring the force required to draw wheel carriages on roads of different constructions."

Word contains consecutive vowels 'EI' in between alphabets p & rameter is misspelled as 'AI'
Wrong Spelling:  p-ai-rameter 
Correct Spelling:  p-ei-rameter 
Find more wrongly spelled words of Peirameter to spell it well.