Beginning July 1, Caltrain riders will have to pay more to buy paper tickets and eight-ride discount passes.

The Peninsula Corridor Joint Powers Board approved the higher fares Thursday to not only generate additional revenue for Caltrain but also to encourage riders to switch to Clipper cards — plastic passes that can be used on several Bay Area transit systems. The price of those cards won’t increase.

Riders who stick with cash purchases will pay an additional 25 cents for one-way paper tickets and 50 cents for one-day tickets, according to Caltrain spokeswoman Christine Dunn.

Caltrain also will slice the discount riders get for eight-ride passes from 15 percent to 7.5 percent. And all eight rides must be taken within 30 days of purchase instead of the current 60 days.

The San Mateo County Transit District originally proposed steeper increases but tempered them after riders sent protest letters and spoke out at community meetings.

Another increase may be sought next year if at least half of the current paper ticket buyers don’t switch to Clipper cards by March 1, 2013, Dunn said.

Email Bonnie Eslinger at beslinger@dailynewsgroup.com.