After searching and driving around to various tool and building hardware type shops, I've found the cheapest and the best quality castors at this online business. They are of better quality than those I bought not so long ago from another business and were cheaper despite the postage which comes with an online order. Rubber castors (blue/black) 80mm with a load capacity of 130 kg. Just amazing. Ordered one day, arrived the next. Price was $9.74. Perfect for making trolleys for heavy machinery. They have light/medium/heavy duty castors, pneumatic wheels and spare parts. Great service and price. Very happy, will be ordering more.