Advans are around 1kg lighter than the R888s, which is worth the extra premium in terms of rotational inertia alone, it's equivalent to around 2.5kg on the wheel!
Take into account the extra grip from the A048 and it is far superior to the R888 and worth the extra. I don't think Toyos are even that far behind the Yokos in terms of price now, so the choice is even easier!
Advan's are better im my opinion. We use both of these at work and i have personally done comparison test's. I found the R888s after several heat cycles went to hard and the rubber compound did not seem to be as grippy compared to advans in the same period of time and cycle. I thought the advans seemed to take longer to get hot but when they were that was it! grip!
^^^^ so not tru, im running a shock and spring combo and i feel its better than the coilovers i used to have.
as to the tyre the 888s wear out quicker and the heat cycle has a very short window, which is ok for short runs.
the A048 are an ok tyre now they do last longer as they are a harder compound and do grip better, but i find them to be out dated now with the A050s
As said above the advans are lighter and have more grip than the r888s but i used the r888s and they are very good, if you were going to be doing lots of track days it would be worth spending the extra cash and getting the advans but if its just for everyday use and occasional track just get the toyo r888!
I use to run A048's on my glanza there great tyres the only down fall is they take quite a while to warm up and you have to drive pretty hard to get them to the correct temp which fine on the track but on the road it sucks pretty bad and there hopeless in the wet lol
The R888 hit optimum temp alot quicker but there not as much grip as the A048's and they tend to have a fair bit of flex where as the Advans are solid.
So in my opinion if you're using them for many track get the Advans if mostly road get the toyos.
The difference in performance is not noticible in the dry IMO.
However when its wet, the Advan's have much more grip than the 888's. For that reason alone i would say that the Advan's are better.
I would nearly describe 888's in the wet as being dangerous. They have no grip at all when it rains.