Officers from the Driver and Vehicle Standards Agency (DVSA) stopped a taxi in Cwmbran and found two of the tyres were heavily worn.
The legal minimum tread depth is 1.6mm and both tyres were below this amount.
A spokesperson for DVSA Enforcement said: “A taxi driver in Cwmbran has received a £990 fine, including costs and victim surcharge at court.
“They were driving a vehicle with two front tyres below the legal limit of 1.6mm (tread depth). Their licence was also endorsed with penalty points.”