slippery rear

[greeny4704]

When i first bought my bike it had original dry rotted tires on it but i only had about a months worth of riding season left so i rode it til it got cold i switch to the kenda cruisers the next season and put about 3-4000 on them amd the whole time my rear felt very slippery around corners and this season is still the same could it be that my shock is super cushiony? (If thats actually a word lol)flip or is it me or the tires?