A promotion by online tyre seller eTyres claiming prices 40% lower than leading tyre depots has been banned after checks by the Advertising Standards Authority.

Claims on its website, viewed in October 2011, stated: "40% CHEAPER than leading tyre depots* ... our fully-inclusive prices are always low - up to 40% cheaper than the leading high street tyre chains".

However after a complaint from rival Hometyre Group, the ASA investigated and ruled the claim was misleading.

The ASA considered that, in the absence of the words "up to", consumers would understand the claim "40% CHEAPER than leading tyre depots" as an absolute claim that applied to all products.

It said evidence submitted by eTyres including shopping research based on phone calls to tyre depots, but noted there were variations in the prices recorded, differences to the quoted online prices and the savings claim was based on a selection of eight tyres only.

"We acknowledged that eTyres believed they were 40% cheaper on over 10% of their products. However, since we had not seen evidence of that, and because the claim implied all products were 40% cheaper, we considered the ad was misleading," said the ASA.

"We told eTyres to ensure that, when competitor's online prices could be taken advantage of at a depot, future price comparisons should take into consideration competitor's online prices.

"We also told eTyres that they must hold adequate evidence to show their products were cheaper than their competitor's products before making that claim in future marketing communications."