Big bikes will be banned from national parks to keep the forests in their pristine state and undisturbed, according to the National Park, Wildlife and Plant Conservation Department.
The department said the ban will go into effect before the New Year when many holidaymakers head to the parks for the long weekend.
The ban on big bikes comes after the government recently imposed a ban on alcohol being consumed in national parks.
The department has also announced parks would be off-limit to pets and noisy revellers during the New Year holiday. No-smoking signs have been erected at park entrances and at sites within the parks
"We'll strictly prohibit them [big bikes]," department chief Thanya Netithammakun said, adding their loud noise disturbs both visitors and wild animals.
Some biker groups have organised trips to national parks including Khao Yai, a large forest complex covering areas in Nakhon Ratchasima, Prachin Buri, Nakhon Nayok and Saraburi. Motorcycling on northern Thailand's winding roads is popular, with thousands of yearly side trips to national parks by bikers from home and neighbouring countries.
Noise pollution is the main reason the department cited for the ban. Late last month the department announced it does not want revellers who generally cause disturbances. Those who defy the rules will be kicked out of the parks - but now, visitors on big motorcycles will not be allowed to enter at all.
Strict measures are to be enforced to better manage a large number of tourists in protected forests, especially during the long holiday. Last year up to 12.9 million holidaymakers visited national parks nationwide.
Though they brought in revenue worth 2.4 billion baht, many of them left problems behind, according to the department.
Mr Thanya said earlier that an alcohol ban was being imposed because booze is a factor that can lead to conflicts and other unruly behaviour, which destroy the parks' peaceful atmosphere.