Warning not all pneumatic trolley wheels are the same - if the specification does not say 4 ply heavy duty, this means it is economy 2 ply.
Printed on the tyre you should have 16 x 4 or maybe 4.80 x 4.00 - 8. To fit 25mm axle and total size measures 40cm x 10cm. The bore measures 25.5mm wide x 65mm deep (i.e. 65mm+ is the clearance you will need on your axle) . The rim has a diameter of 220cm.
Important: The hub is fitted with what looks like removable inserts - they are not. This wheel does not have inserts, so they can't wear out or get damaged.
Please note that these are 4 ply specification - this means that they are rated for a higher load than 2 ply. Also note, the tyre is a "Kings Tire" (not a typo) which is the highest quality tyre in production.
In practical terms this means that no matter what boat they are used with (Optimist upwards) - they will be far more durable and less likely to puncture.
2 Ply tyres are cheaper but we do not recommend them for any class of boat
We buy huge numbers of these wheels which allows us to sell them at less than the price of the 2 ply tyres.
It is common for the lower specification 2 ply tyres to be sold for £19.95 i.e. Indespension and most Marine retailers. Read more
Even when these wheels are being used for none marine use i.e. wheel barrows, off road machines etc their 4 ply specification and quailty tyre will mean they last longer and are more puncture proof than an economy tyre or 2 ply tyre.