Rear tire aspect ratio (performance)

[kawiben]

So, as some of you may have read I recently posted a thread about lowering the front end of my '04 636. I wanna turn it into a track day/race bike.

The other thing I was looking at doing, was going from a 180/55 rear tire to a 180/60 or 185/55 tire. The way I figure with how the aspect ratio works on tires, and more specifically bikes, is that if I increase the aspect ratio by having a slightly fatter tire on the same rim, the rear tire begins to take on more of a triangular shape. It should come to more of a point at the center of the tire. Perhaps making it harder on the tire (as well as the rider) to maintain speed in a straight line. However it should help "throw" the bike into the corners a little better.

My reasoning on this is to decrease the amount of time and effort to transfer the bikes weight to go from full lean to the left to full lean to the right.

If anyone out there is familliar with what I'm talking about, could you please tell me if I am right on my reasoning or am wrong, along with any other feedback that my pertain to the question.

[ervins]

Ok so I am in sorta the same position as you but am going opposite direction. Stock tires on my 10R in the rear is a Dunlop Qualifier190/55 compared to what half the riders or those who responded that they ride 190/ 50. The 55 helps in turning, but I really have no problem leaning or getting it to "do as I want". However, allegedly, the 190/ 55 offers more contact patch and easier turn in (ZX-10R requires more rider effort) which is also a key component of turning...I am thinking of going 190/50 for reduced height which is supposedly around 3mm when measured but the difference is supposedly negligible since the bike (10r) requires you to lean (hence effort). Currently, I like the way the stocks are going...Not my favorite tires but if I am basing turning, it is good so far...When I was leaning yesterday on one big sweep on my way home, it was nice...I can see the 50 effecting it a little but not too much since I have to help it along the way. Hope that helps...One of the best advices...Try what you are looking to do.

[Thmastr]

ookay I will try to tackle this...

so.. are you looking @ slics?

The zx6rs are among the few bikes (if not the only bikes) which come stock with a 65 profile tire on the front. there are very few high performance tires that are made in the 65 profile for the front... why not just put on the 60s? this will lower the front a bit more, and will give you a wider variety of tires to choose from. However I would only go to a smaller profile if I am tracking my bike... If I ride street with the uneven surfaces we find I like to play it safe and either stay at the stock, or go up to the 70 profile (another more standard size)

this is with the front.. as you said you can take the rear and raise it to the next profile size. Again that would change the geometry slightly so that you would have an easier turn in... your loginc makes sense to me but then again I am not a tire expert.

Ervins:

you are talking about making your profile lower? (your tire wall?) If this on the back it will change the geometry slightly to give you a harder turn in.. and also at a 50 profile tire the wall is tiny and I know the roads you ride on! you are increasing the likelyhood of messing up a rim from a bump (but this is just me trying to play it safe)...

While your logic contradicts that of the person above you. You are both right... the beheaibour is there. however raising the back, (or lowering the front) can be a bit more noticeable than changing withs.

[Freakinout]

If you're going with a track bike, you will go through tires quite quickly... so you might need to just adjust them from set to set and see how you like them.

[ervins]

The 190/55s on my rear turn nice...Actually this bike turns really well. With the front lower half and inch, I can essentially take that 190/55 and go to 190/50 to save some height...All I know is that these Qualifiers and almost every 10R forum will agree. Suxors!!! They take so long to warm up that I went 20+ miles before I felt like it was gripping well...Pirelli!!!!