I had the same problem ( sticky deteriorating wheel )
I got a cover from supercheap ..... Thinking about it now it may be a size too small...... It was a real bastard to get on .... The first one split whilst putting it on but luckily this was in the carpark went in and got another and gently stretched and coaxed it on, took about 15min and lot of effort but eventually got it on. Now it's a lot better.. It's slightly spongy .. But the best part is the thickening of the steering wheel, feels a lot nicer.