The chain's Brexit-supporting chairman Tim Martin said leaving the customs union on October 31 would allow the Government to end ‘protectionist tariffs’, which he maintained would reduce prices in pubs and supermarkets.
More than 600 Wetherspoon pubs will sell a pint of Ruddles for £1.69 from Friday, with a further 160 offering a pint for £1.59 or less.
Around 36 pubs will sell a pint for £1.39.
It is the latest Brexit-related move by Wetherspooon, which has shown its commitment to leaving the EU by selling more English and Australian wines over European brands.
Tim Martin said: ‘At the current time customers and businesses pay tariffs on thousands of products which are imported from outside the EU.
‘These tariffs are collected by the UK Government and sent to Brussels. Provided we leave the customs union on October 31, the Government can end these protectionist tariffs, which will reduce prices in supermarkets and pubs.
‘In order to illustrate this point, Wetherspoon has decided to reduce the price of Ruddles bitter, brewed by Greene King.
‘A lot of politicians have misled the public by suggesting leaving the customs union would be a 'cliff edge' or 'disaster'.
‘This is the reverse of the truth. Ending tariffs will reduce prices.’
Ruddles is one of the most popular beers sold in Wetherspoon pubs. Where it isn't available, Greene King IPA or Caledonian Deuchars will be included in the reduced price.