[QUOTE=Orthonormal,Sep 23 2010, 11:56 AM]Steve, I just noticed this...how come you have the AP2 going to 60MPH in 2nd gear?

 

So, short answer, you are assuming 275 rear tires?

 

Ah, I think I might see what you're getting at. Differences in the acceleration curve due to shorter/taller tires? In which case a fair comparison would be to have equal diameter tires on the AP1 and AP2?

 

Forgive me if this is a repost

We already know that toyo makes a 245/35/17 R1R

we also already know that that gives a nice gearing boost to the AP1

however, we worry that the reduced treadwidth may be a disadvantage

I just poked around on the Hankook and Toyo websites and noticed the following

Hankook 255/40/17:
diameter: 25 in
Tread width: 9 in

Toyo 255/40/17:
Diameter: 25.2 in
Tread width: 9.4in

Toyo 245/35/17
Diameter: 23.8 in
Tread width: 9.2 in

So... the toyo 245/35 is wider than the Hankook 255 and only .2in narrower than the toyo 255... while giving a 5.1% gearing boost, enough to lower the AP1 top speed in 2nd gear from the 64-65mph range to 61mph... moving the powerband down like that could be a huge advantage and it looks like you are not giving up much of anything in the way of treadwidth

also, the 245/35 is measured on an 8.5 in rim, so in all likelyhood you are actually loosing less than .2in in treadwidth to the 255 and gaining more than .2 on the Hankook....

I think I may be trying the Toyo 245/35 next time around, even though I was originally planning on trying the Hankook next

 

Tread width doesn't change with wheel width change, section width does. How flat that tread is to the ground is another matter.

John/Steve - I have DL1 datalogs that confirm 59.8mph on the limiter in 2nd on 275/40-17 A6's.

 

Thanks for posting! Guess my butt dyno was right.

Buy a CR if you can. They are awesome.

 

Why is the Hankook 255/40-17 tread width so narrow? Even Hankook's new 245/40-17, on the website, is showing a 0.1 inch larger tread width than their 255/40-17. Is it possible they measured their 255/40-17 wrong? The 18" 255 is listed with a 9.5 inch tread width. Can this be easily measured by hand for confirmation?

 

I'm certain that the kook is wider than my Star specs on a 9 in wide wheel.

 

They seem bigger than 9" to me...





Edit ... Tires have 40psi in them so they are a bit curved. With the weight of the car pushing down on them, I'm sure the contact patch is at least from the points where I measured. I'm guessing at least 9.25" on the 9" rim. The angles make the ruler look off, but I double checked.

-Marc

 

I think being able to raise the limiter in an AP2 is a significant advantage.