The number of Welsh 'A' roads in a poor condition has increased by more than 50% in the three years up until 2011.
Councils say that a "significant problem" exists and are borrowing tens of millions of pounds from the Welsh government to repair damaged roads.
But the Welsh Local Government Association said Welsh roads will be in a "reasonable condition" this winter.
The Welsh government also said stocks of gritting salt are almost double what was held in the autumn of 2010.
The latest figures revealed by the BBC show that recent harsh winters have led to an increase in potholes across the country.
The statistics show that in the three years up to 2011 the number of main 'A' roads in a poor condition increased from 4.3% to 6.6%.
Updated figures for this year from the Local Government Data Unit show that more than one in every eight roads in Wales was in a poor condition - a rate of 13.5%.
Councils are responsible for the maintenance of 95% of roads in Wales, while the Welsh government looks after the remaining 5% of trunk roads.
An annual survey by the Asphalt Industry Alliance (AIA) suggested that it would take 17 years to clear the backlog of potholes in Wales, compared to nine years in London and 11 years in the rest of England.
AIA director David Weeks said: "Wales has been the poor relation in terms of funding and maintenance and condition of roads.
"There are a lot of reasons for that - there's a lot of rural roads in Wales which are not a high priority.
"There's also a lot of very important roads within the network linking communities which have been allowed to deteriorate, which the survey has flagged up."
He said another factor was the frequency of road surfacing - in Wales that gap can be more than 70 years, compared to 45 years in England and Scotland.