OVRsi

trust me people i could not find an exact answer on a search and I don't want to make a wrong decision. I am going to order 15x6.5 wheels, and 205/55/15 S-03. Will this combo work correctly for frequent autoX and street? I guess i do not understand the effects different combos of #s have on the response of your car. the car is a '99 Si, so i think the OEM size is 195/55/115. Thank you for any input. -jake-

XrcR6

First number is width in mm, second number is the aspect ratio (% of the width equaling the sidewall height), last number is the rim size (in inches) that the tire is intended to fit on.

So while that is a wider (205 vs 195) tire and would help with lateral grip, its also a taller tire. And that is going to affect your gearing. Basically you will accelerate slower since the side wall will be be taller and you now have a tire/wheel assembly that has a larger outer diameter (55% of 205 is bigger than 55% of 195). How much slower, can't really tell you but it shouldn't be that drastic. Also your speedo will be slightly off, should indicate slower than what you are really going.

TireRack.com explains all this and should have the recommended +/- percentage you should stay within. They also list the exact OD for that model tire:

http://www.tirerack.com/tires/Spec.j...+Pole+Position

That may link may not work after a while, just search by brand and look up the Bridgestone Potenza S-03's... the headings in each column of the spec. table will tell you everything you want to know about tire specs.


[Modified by XrcR6, 11:34 PM 3/4/2003]

OVRsi

thanks for your input. I know how to read the tire, and the ratio, mm, blahblah. I guess i wasnt sure which size S-03 to get to stay closest to OEM size or what will work well with my new 6.5x15 wheels. thanks. -jake-

XrcR6

Well, from the performance standpoint I'd go with the 205's then. Corner speed is paramount in competition. That's also the max. width for a 6.5" wheel anyway. You can squeeze on bigger, but then they start to "snowcone" and you'll get wierd turnin.

You may actually want to try the 205/50/15 S-03, it will give you the best acceleration (quicker than stock) and widest tire. Doing the straight math:
205-50-15 is 23.07" OD
195-55-15 is 23.45" OD
205-55-15 is 23.88" OD

The actual sizes listed for that model (since all manufacturers vary a little from the mathematical ideal):
205-50-15 is 23.1" OD
205-55-15 is 23.9" OD



[Modified by XrcR6, 11:55 PM 3/4/2003]

OVRsi

you are a good man, people like you make me learn. -jake

Geezer

This is the math I did, and picked the 205/50/15s. Better acceleration, shorter sidewall, and (if I remember correctly) lower price.

Todd00

Don't put a 205/55/15 on the 99-00 Si. Way too tall of a tire for a motor with that little amount of torque.

205/50/15 is by far the best bet. In reality, a 195/50/15 would probably be good as well for autox because it would allow even shorter gearing and quicker acceleration.

OVRsi

thank you much fellas, i follow.

Art Vandeleigh

i also agree that the 195/50/15 might be a better choice.

ActiveAero

< wears 195/50 as well and likes it.

Todd00

Sent you an IM OVRsi.

asmallsol

also the 195/55/15 are alot cheaper. Go to tirerack.com and they have the S03's for only 79 a tire. I will be ordering them this week