From Lexicanum

A Land Speeder Squadron is made of between 1 and 3 Land Speeders of varying types.

They are made up of a mixture of any of the following:

• Land Speeders¹
• Land Speeder Tempests¹
• Land Speeder Tornados¹
• Land Speeder Typhoons²

Sources

• ¹:Codex: Space Marines (4th Edition)
• ²:Forgeworld

Space Marine Vehicles

Rhino Chassis	Rhino • Damocles Command Rhino • Razorback • Vindicator • Whirlwind • Predator Annihilator • Predator Destructor • Baal Predator • Sabre Tank Hunter
Land Raider Chassis	Land Raider • Land Raider Crusader • Land Raider Redeemer • Land Raider Helios • Land Raider Prometheus • Land Raider Ares • Land Raider Terminus Ultra • Hellfire Land Raider • Land Raider Spartan
Dreadnought Chassis	Dreadnought • Furioso Pattern • Mortis Pattern • Ironclad Dreadnought • Siege Dreadnought • Venerable Dreadnought • Grey Knights Dreadnought
Land Speeder Chassis	Land Speeder • Land Speeder Tornado • Land Speeder Typhoon • Land Speeder Tempest • Land Speeder Storm