How much of a difference is it really going from 195-55-15 to 205-50-15 ?

 

Don't worry about it, noob.

 

I lost three tenths going from 205/45/16 Paradas to 215/45/16 Azenis if that helps you out any.

 

yeah man...damn noob didn't even know where to buy brake fluid...

 

haha noob

I bet it will be slightly slower because it will weigh more..

 

if you get the azenis they are definatly heavier

 

Could that have been due to a difference in tire compound, tire weight, temperature of the track that day, bad tank of gas, etc?

How are you sure only the overall diameter of the tire was the culprit?

You could have lost 4 tenths just by not knowing how to launch on the Azenis.

You have to eliminate all other possible variables before drawing a conclusion.

 

HAHAHAHAH!

I always thought a larger diameter rim/tire combo would make the car accelerate slower. If anything the wider tires would help acceleration due to traction from larger contact patch. *shrugs*

 

When I went from 195/55/15 tires to 205/50/15 tires, my car handled much better and lap times went down significantly.

My input is useless though, as I went from 195/55/15 RE010s to 205/50/15 Kumho V700s.

 

It may very well be compound related, but not the track conditions. I race in a club series at the strip with some friends (we're third place out of 80 clubs too!) and I've been out there with the Azenis about 6 times. Same results every time, at least it's consistant.

I've made about 35 or more passes with the new tires and can cut a 2.30 60' (sounds slow, but for a FWD car on street tires at 6000 feet above sea level it's pretty good) consistantly on them.

Personally I think it's weight or rolling resistance from a wider tire. Most likely a combo of the two.

 

Same here!

I went from the stock 195/50-15 RE-010s to the 205/50-15 Falken Azenis and my ITR handled like it was on rails! I had a slight camber up front so the turn in was awesome w/ the Azenis.


[Modified by ITRbroham, 12:15 PM 8/6/2002]

 

It does. It's just like putting the car into a higher (taller) gear.

However, a 205/50-15 tire should have a SMALLER outer diameter than a 195/55-15. Except that the Falken Azenis aren't exactly 205/50-15.

Nope. First of all, the size of the contact patch doesn't change when you change tire sizes; it's strictly a function of the car's weight and the pressure in the tires. As long as you have 33 psi in all four tires in a stock ITR (2640 pounds), the area of your contact patches will total 75 square inches (=2640/33), regardless of the width of your tires.

People often advocate wider tires because the SHAPE of the contact patch changes, even though the SIZE doesn't change. (The contact patch becomes wider side to side, although narrower front to back.) But the alleged advantages of the wider tires are in cornering, not in acceleration or braking.



[Modified by nsxtcjr, 2:20 PM 8/6/2002]

 

I'm having a hard time envisioning that. Why would the front to back contact get smaller if the width changes but not the diameter?

 

I guess it's all neglible. Thanks guys. No thanks to the ricer boys Reid, BlueR, and typeRice 599.

 

The azenis are 5 lbs heavier that REO10's right?

So if you do the vodo math, I think that comes out to 14 whp?
I guess that equals out to around .3 - .4 on the 1/4 mile
https://honda-tech.com/zerothread?id=100751





[Modified by jond, 4:00 PM 8/6/2002]

 

Because the downward force of gravity must equal the upward force applied at the bottom of the tire, on the area of the contact patch.

Click here to see an illustration on Tire Rack's website.

 

It is true that wider tires commonly have better traction. The main reason why this is so does not relate to contact patch, however, but to composition. Soft compound tires are required to be wider in order for the side-wall to support the weight of the car. softer tires have a larger coefficient of friction, therefore better traction. A narrow, soft tire would not be strong enough, nor would it last very long. Wear in a tire is related to contact patch. Harder compound tires wear much longer, and can be narrower. They do, however have a lower coefficient of friction, therefore less traction. Among tires of the same type and composition, here is no appreciable difference in "traction" with different widths. Wider tires, assuming all other factors are equal, commonly have stiffer side-walls and experience less roll. This gives better cornering performance.

http://216.239.39.100/search?q=cache...art=2&ie=UTF-8

 

Oh boy, not this debate again. nsxtcjr is correct. The contact patch will stay the same size, and will become wider with less contact front to back.

There were some discussions on this a while back.

Edit: Sorry, didn't mean to beat it to death. I had the reply sitting on my screen for the past 30 min.


[Modified by Floyd, 1:47 PM 8/6/2002]

 

 

I'm going to give an extreme example because extreme examples are easier to understand sometimes.

If you put a 1000mm wide tire on a 16 inch rim, it will have the same amount of rubber the ground as a 205mm wide tire of the same diameter?

It doesn't make sense. If you put a paper towel roll on a counter it has X amount of carboard touching the counter, it you cut the roll in half it has half as much carboard on the counter. Now I know that rubber flexes under load, but there's got to be some corrolation between the paper towel analogy and a tire.

 

Under the same pressures, your 205 vs. 1000 mm tires will have the same area of contact. 1000 by 1 mm for instance, vs 205 by a little less than 5 mm. an example. They have to support the same weight, and under the same pressure will by default take up the same area on the ground.

 

Yeah, that's what I meant. I agree totally witht the last sentence!

Thanx for the clarification, Ken

 

So the if the pressure is the same it will not change the contact patch. Gotcha there.

Now what about different compounds of rubber and varying stiffness in the sidewall? You can't tell me that all tires are going to flex into the same shape no matter how stiff the sidewall is.

 

 

No, I'm not. The SHAPE of the contact patch does indeed change with the width of the tire, the compound used, etc.