On the face of things a pretty simple subject? Well no frankly...  Well it can be, if you don't care and anything will do!

But some of us care about comfort, punctures, longevity, grip, controllability and even how they look!  A powerchair to its user is his/her legs after all.  Wherever you go you are seen with it. It is associated with you like it or not.

Personally I have been using black tyres for 12 years now and live in a fully carpeted house. These are brown and grey carpets. There are no black marks on my carpets anywhere. The only time black tyres seem to leave black marks is if either the tyre or the carpet is damp. Even slightly damp and it does happen. It wipes away with a carpet cleaner solution and a cloth. But if you take care and use common sense its really a non issue and It has not happened for about 5 years once I realised what caused it! 

They do leave marks on paints if you are clumsy enough to hit them but I don't anymore. I learned to be careful|! Of course with a mid drive powerchair with four casters swinging around in front and behind you this is harder to achieve. Another reason I prefer rear drive powerchairs. In any case it wipes away with a damp cloth.  I have brown, and grey carpets though. You might want avoid them if your house is full of white carpets!

The manufacturers offer these at great expense as a solution to the flat tyre problem. They are harder to "push" and therefore waste battery power and increase the average depth of discharge of your batteries and therefore shorten their life at the same time as giving you and your back a horribly harsh ride. Why do you suppose cars and motorcycles don't use solid tyres? If you like that sort of thing then go for it! But my back or my batteries cant stand it...

What they should do is fit proper tubeless and puncture resistant tyres like these below (as I am currently fitting to this powerchair) But that would mean some improvement and some progress!  Some evolving... They don't seem keen on that.   They give a nice smooth ride, don't tire batteries, and are al but impossible to puncture.

Maybe they would need to get some made in grey. That would mean a phone call. And some tubeless wheels. All available off the shelf mind. No, tubes will be ok for the disabled -- they were for the last 30 years! They don't know the difference!  Well some do.  And the more people that read this the better.

The best type of tread pattern/tyre size/type for your drive wheels? Ideally if you only ever go on dry grass, roads or pavements or carpets then you need a "slick" type tyre. That is one with NO tread pattern.  They wear better, roll easier, don't damage lawns or carpets as you turn, and are less prone to punctures. These are pretty hard to come by in the sizes we need for powerchairs so the next best thing is something like this below

Caster wheels should always be rounded in profile and smooth. And preferably tread FREE in an ideal world. Even on an off road powerchair... I have seen a large number of clueless dummies and that includes some manufacturers who fit "off road" style caster wheels (tyres) to off road powerchairs. They do it probably unthinkingly but its just wrong! A perfect caster would be a hover wheel with NO grip.

Because a castor does not "want" grip! Its job is to simply go exactly where it is pushed whatever direction that may be. Tread or any extra grip just hinders its operation and wastes battery power and upsets and steering response more than a smooth caster would have done. Ideal caster for all on or off road powerchairs is a tread free (or as close as you can get) rounded profile tyre. 

What NOT to buy opposite for any caster >>>
unless you don't quite understand basic physics...

Rounded profile because otherwise as it comes up to an edge at a slight angle (a raised paving slab alongside you for e.g.) it will bounce away rather than ride up it. The bigger and fatter the castor wheel the nicer the ride and the easier time the caster wheel and you have.

Mine are 9 inch (measured) and a claimed 10 inch and about perfect for every outdoor/indoor dual purpose powerchair. Actually they are 3.00 x 4 tyres. In black of course since they are £20 for 4 with tubes! (About 1/5th of the price of mobility grey ones...)

What to buy for your caster wheels. You are mostly looking at the shape of the tyre here not the size! The size is whatever fits your chair. And smaller is better indoors and bigger is better outdoors. And wider is better off road...  I am using these on my off road powerchair since they are almost smooth so work good indoors and out and off road.