KIDS2000

Hi guys, as I understand the current S2000 wheels are:
16x6.5 with 205/55/16 which gives overall diameter of 633mm
16x7.5 with 225/50/16 which gives overall diameter of 632mm

The Advan model6 that will go on my car soon will have the tyre specs of:
17x7 with 215/45/17 which gives overall diameter of 625mm
17x8 with 235/40/17 which gives overall diameter of 620mm

The 17" combo + Tyres, though wider, will be even lighter than stock...

so My question is, how much difference will it make in:
Speedometer Reading?
Straight line acceleration?

Cheers~
Yong

xtc@9k

Without even doing the calculations the speedo would be almost the same as well as acceleration. There is only a 12mm difference from your stock diameter in the rear and you could almost have that variation from tire pressure alone.But if there is any difference in the speedo, it would read faster than you are actually going a in theory you would be able to accelerate faster.

Phantom

KIDS2000,

235/40/17's tread width might not be wider than the stock S02's (8.5 inch).

My 245/35/18 Toyo T1-S are not as wide as the stock S02's.

What kind of tires are you planning to buy?

josh3io

i'm sorry, but a 12mm diameter change from pressure would be scary.

it will however have minimal effect on the spedometer, if anything it would help you out by telling you you're going a bit faster since there are more revs of the wheel per given time period.

You will also have a very slight, probably not noticeable increase in torque to the ground. Remember that the wheels act like a final gear set: by decreasing the diameter you decrease top speed and increase torque.

Let's say that the overal gearing between the engine and the wheels is 6.1:1 (sake of conversation), then at 6000rpm the car is moving 72.84 mph with a wheel rolling diameter of 632mm. drop diameter to 625mm and the speed is 72.03mph. so you'll be off by less that 1mph for that gear ratio.

FORMULA:
1 inch = 25.4 mm
T = tire diameter in inches
G = gear ratio (transmission + final drive)
mph = (rpm * T) / (G * 336)

KIDS2000

Phantom,
Plan to get Falken FK451 Tyres...From what I gather I hear they are a good all round street tyre.... I dont plan to bring my car to track much so should be alright

For the front i choose a 'skinny' tyre as possible due to the offset of my wheels which i understand to be +45

The rear is another story....
For the rear i might go 245/40/17 but means i need to look for different tyres...also scared of rubbing....
Arrrgghhh!!!!

Either way, I will be very cautious in my first few weeks with the new wheels+tyres...