High speed towing (in excess of 5 mph) or towing over rough or uneven surfaces are the primary cause of premature caster wear or failure. Jack caster wheels are usually less than 10 inches (254 mm) in diameter and at excessive wheel speed, usually above 8 mph, the caster assembly will oscillate causing excessive heat, wheel tread wear and bearing failure. For Malabar mobile axle jacks (45 ton to 90 ton) a low cost jack transporter (or other combination units) is available for transport at up to 20 mph. Refer to the jack accessories, for information.