Rural roads are being "left to rot" because local authorities are not being given enough money to repair them, an industry report has claimed.
Rural roads are losing out, the report says
The Asphalt Industry Alliance (AIA) said the problem of potholes is so bad it will take 12 years to correct.
In June, Wales' 22 local authorities called for more than £20m in extra funding for road improvements.
A spokesman for the Welsh Assembly Government said an £8bn transport plan had been announced last December.
Sixteen Welsh councils took part in the AIA study of the pressures on highway engineers' maintenance budgets.
The survey found non-principal roads in rural areas are suffering the most, with councils planning to resurface them only every 75 years. The recommended time is every 20 years.
The backlog of repairs in Wales would take more than 12 years
Unclassified roads face a wait of 86 years before they see a new surface coating, according to the study.
The report also said the poor quality of some country roads is a risk to both road users and the Welsh rural economy.
A previous study by the AIA found Wales received a sixth of the highways maintenance budget per road length compared to London and half of that spent road by local authorities in England.
Highways departments in local authorities across Wales were working on an annual budget equivalent to just £1 per metre of road compared with £6 per metre per year in London and £2 in the rest of England, it found.
AIA chairman Jim Crick said: "There appears to be an insidious attitude that rural roads and their condition matter less than roads in build-up areas.
"Larger and heavier lorries are using them more regularly to deliver to farms and collect farm produce. They are used, quite literally, to get the goods to market and they need to be fit for purpose and safe."
In June a report to the Welsh Local Government Association (WLGA) said that much of the extra money that local authorities had received had been spent on day-to-day services.
A spokesman for the WLGA said: "As with all capital projects, capital is in short supply. It does seem as if rural roads are being neglected."
A spokesman for the Welsh Assembly Government said an £8bn transport plan had been announced last December with 40% of that likely to be spent on roads.