The short answer for a Turkish Van
A Turkish Van suits the sturdiest post you can find: tall enough for a long cat's full stretch, wrapped in thick sisal, and anchored by a broad, heavy base. This is one of the larger, stronger domestic breeds, slow to mature and powerfully muscled through the shoulders, and it scratches like it means it. A post sized for an average cat flexes under a Van, and a flexing post reads as unsafe to the cat standing on its hind legs with its full weight pulling down the wrap. Build quality is the whole question here; dimensions and materials follow from the strength of the animal using them.
Sizing for a big, slow-maturing cat
A Turkish Van keeps growing well past its first birthday, and a mature male is a long, substantial animal. Measure the cat at a full stretch, front paws high on a wall, and choose a post taller than that reach so the cat never outgrows the top of the scratching zone. Thick sisal rope outlasts thin wrap under a Van's claws, and a solid wood or heavy composite core matters more than the finish: squeeze and push the post in the shop, and reject anything that creaks or gives. A kitten-sized post bought for a young Van is false economy, because the cat will need the adult version within the year anyway.
The base decides whether the post gets used
A Turkish Van launches onto furniture and lands with commitment, so the base must behave like part of the floor. A wide, weighted base or a post bolted to a heavy platform keeps the unit planted during both the downward rake and any sideways spring onto a perch. Place the post on a hard floor or low-pile rug where the base cannot skate. Vans are also famously drawn to water, and many investigate sinks and tubs daily; keep the scratching post in the dry social rooms where the cat spends its evenings, not in a bathroom the cat visits for plumbing tourism, so the post stays part of the main living routine.
Add a horizontal outlet for low rakers
Many Turkish Vans rake horizontally with real power, dragging front claws forward across a surface. A wide, heavy flat scratcher or a low ramp gives that style a legal target and spares carpet edges. Put it where the cat already performs the behaviour, often near a favourite sleeping spot, since a Van scratches hard on waking. Rotate which scratcher gets a pinch of the cat's attention by moving the flat one a short distance every few weeks; this curious, playful breed investigates anything that has changed position, and renewed interest means renewed use.
Strength changes are the watch-out
A Turkish Van that stops pulling its full weight into a scratch, or that quits leaping onto its perch, has changed the behaviour that defines its day. In a breed this physical, a drop in scratching force or jumping confidence is a sensible prompt for a veterinarian's check, especially as the cat moves into its senior years with a large frame to carry. Enthusiastic daily destruction of the sisal, by contrast, is the picture of health. Note the heavy-duty specification where the whole household will find it before anyone shops: KinsLe's Family Sharing keeps your Turkish Van's profile and care information shared with family, so the replacement post that arrives is built for the size and strength of the cat who will use it.