Hello there Nathalie and welcome to planDisney! How wonderful that you're planning a trip for your son's birthday, I can't think of a better place to celebrate than the
Disneyland Resort!
Unfortunately,
tricycles of any kind are not permitted at the Disneyland Resort. However, I always recommend bringing a stroller for little Mouseketeers since it can be a lot of walking for little legs. We usually bring our stroller from home, they just cannot be larger than 31" (79cm) x 52" (132cm). It's not only a nice break for the kids to rest their feet, but we like to store our jackets for cooler weather, and also bring in bottled water and snacks to have throughout the day as well.
If you would prefer to rent a stroller when you arrive,
both single and double strollers are available to rent for usage at both
Disneyland Park and
Disney California Adventure Park. The stroller rental is located outside of the theme parks, just east of the Disneyland Park Main Entrance. We parents have enough luggage to bring on trips, so this could be a great option!
During your trip, I highly recommend taking your son up to the newly reimagined
Mickey's Toontown in Disneyland Park. There are so many activities for little ones to explore including plenty of places to play and stretch their legs at
CenTOONial Park and
Goofy's How-To-Play Yard!
I hope this information was helpful for your trip planning Nathalie, and if you have any other questions
please do not hesitate to come back and ask!
Have a magical day!
Melissa