Bought a 600 silver wing Scooter with the Trike kit on it

The Back Tire only lasted less than a year . What kind of Tire do I buy to last longer

Tyres are a distance thing, not a time thing. How many miles did you do in the year?

less than 2000

I bought it as a Trike he put a kit on it and the Middle Tire won't last a year any suggestions on a Back Tire to last longer

That’s the one situation where it might be worth putting a car tire on the rear of a motorcycle, since there’s no leaning with a trike. They can last many times more miles and often cost less initially.

It’s called “dark siding” or dark side.”

https://www.silverwing600.com/t7073-personal-opinion-crossing-to-dark-side-tire-it-works-where-and-who-is-the-question?highlight=dark+side

https://www.silverwing600.com/t7073-personal-opinion-crossing-to-dark-side-tire-it-works-where-and-who-is-the-question?highlight=dark+side

I had a Silver Wing with a Tow-Pac wheel kit for a while and could not take the rough ride. No matter what brand kit you have you need enough weight on the bike's rear tire to prevent slippage against the pavement during both acceleration and braking. You could go to a higher number on the shocks. Perhaps the outer tires have more air than needed or there might be some adjustments to take some load off the outer tires.

If the outer tires are out of alignment with the bike's rear tire too much then that will serve to constantly remove rubber from the bike's tire since it is a two to one battle. Actually all three of the tires will suffer excessive wear. I decided that since the load had to be shared by 3 tires the ride would never be suitable to me so I sold that so-called trike at a loss. I still count that sale date as a very good day.

so you think the Outside Tires need less Air. who does alignments nobody in my area

Car tire is your best bet. Nothing to align bike tire just wears the center and doesn't last long. I doubt you'll find the exact size in a car tire but look for something in same diameter as stock tire size.
Tire size charts are online find something close. Reduce pressure since car tire can handle much more weight than a motorcycle tire.

Middle tyre? Does that mean it's a four wheeler with outrigger wheels?
If it is I would guess there is a loading issue onto the rear tyre causing the excess wear, either to much weight carried on the side wheels (causing the middle to hop and slip), too little weight on the sides (causing the middle to carry extra weight) or an alignment issue dragging the rear tyre sideways.
I've fiddled with bikes and trikes plenty but 4 wheels in that configuration is new to me, so I'm curious to know what's causing it.

Edit - I've just realised Wingman has said pretty much the same thing.

Well if folk are calling a maxi scooter with two extra wheels fitted as stabilisers a 'trike', then most have us must also have 'trikes' too'.

Mrs M's currently driving over to Cheshire in ours. We opted for 4 cylinder diesel powered front-wheel drive and fully enclosed bodywork, we don't need helmets either. Tank range is excellent too, but in the current climate the cost of filling up with diesel is very expensive. 

Just between ourselves, I'm a closet Darksider because I had two car tyres fitted to the front wheels of our 'trike' a week ago today.

These four wheeled 'trikes' seem to be catching on as they’re everywhere, another good thing about 'trikes'  is there's none of this silly biker waving when you spot another one. 

Many moons ago a mate had a rare old Citroën 'trike', whenever we met another such contraption we would wave to each other. Mostly I think it was surprise that two of them were running well enough to be out on the road at the same time.