[StyleTEG]

Went to the strip today with Liebernoodle, and we decided to swap cars for one run (just to see the difference)

He has 205/50/15's , I have 195/50/15's. So his are alittle larger than the stock ratio/size, and mine are alittle smaller.

So my gear ratios should be artifically shorter than his and stock. But it seams like it made a huge difference, I was in 4th gear for at least a second or two before I crossed the line, where his car would just be ending 3rd as he crossed.

I would think this would be good for acceleration, but at the same time maybe an extra shift is slowing my down somewhat?

Also, is it causing my miles to rack up quicker than it should? Seams like not only is it decreasing the value of my car, but it is throwing off my maintenance intervals and such.

Thanks much for any insight!

 

[cheezthis]

I used to have 195/50/15's on mine as well, and I noticed the speedo and such were all off a bit. I did notice the acceleration factor between the two, I'm now using 205/50/15 (which is actually smaller than the stock diameter still).

I thought about the whole racking up miles faster, but I didn't mind. The resale value on our cars is good, even with high miles.

And all the questions you raised about shifting slowing you down or speeding you up...I've wondered the same thing before. Maybe someone else could shed some light on that, or possibly even do a test.

 

[SurferX]

What was the trap speed of your car vs. his car?

 

[StyleTEG]

Mine was almost always 86 mph, where his was 82 - 84.

I have i/h/e, where he just has /e which seams reasonable for the difference in trap speed.

 

[SurferX]

I'm thinking you had to shift simply because you were faster. Usually on non-VTEC Integras I notice they seem to top out 3rd right at the end when they're in near stock form. once you have the power to get to 4th gear there's no looking back. Hopefully as you add the mods you'll have the power to shift into 4th sooner to achieve higher speeds and quicker ETs.

 

[StyleTEG]

Excellent, thanks much.

So its more of the power difference than the size of the tires. I knew that the smaller tires would make some difference in the speedo/gearing, but I was really unsure if it could make that much of a difference!

 

[MichaelDelaney]

were you faster in time? forget the trap speed...that's a red herring.

 

[StyleTEG]

Yup, I was faster by roughly .3 -> .6 depending on the run

 

[adamones]

Ok I know Im bringing this thread back from the dead, but Im still trying to understand this better. I know that taller wheels = taller gear ratios, but does that actually produce faster times?

If a stock GS-R ran a 1/4mile with 15s would it be faster or equal to a stock GS-R with 16s? I was just wondering if bigger wheels actually help improve your speed, and if they do whats the best size for the fastest speed?

 

[96dc2]

It's not taller wheels, it's taller tires=taller gear ratios. You can have a larger wheel, while still retaining near-stock tire size. With a larger wheel you'd worry about the weight.

 

[Louse76]

Right, the smaller tire artifically gives you tighter gearing, which means that you are putting more torque to the ground.

Can someone help me come up with an equation that would tell me how much more torque is being put to the ground with one tire size vs another?

Using the stated 205/50/15 vs 195/50/15 is what I'm really interested in seeing.

 

[jawz]

I was just wondering but is'nt 195/50/15 and 205/50/15 the same size? Is'nt the only difference is that the 205 is a wider tire with more weight than a 195?

 

[dexmix]

the 50 is a percentage of the width, so obviously 50% of 205 is bigger than 50% of 195. as found here

 

[Louse76]

nope.

 

[jawz]

you learn somthing everyday.

 

[timpac167]

Can someone help me come up with an equation that would tell me how much more torque is being put to the ground with one tire size vs another?

Using the stated 205/50/15 vs 195/50/15 is what I'm really interested in seeing.

Don't know if this would work, but give it a try and lemme see what you get.

Basic formula for torque on to the ground is the torque at the wheel multiplied by the gear ratio of the gear you are in, and finally multiplied by the final drive. When changing the tire size, you are effecting your final gear ratio.

Go the the Articles gear ratio calculator and play around with it. I did and I find on my transmission [ GSR tranny plus JDM 4.78 FD ] going from a 205-50/15 tire to a 195-50/15 tire, I see that my effective FD goes up to 4.9.

Then you back track, recalculate your numbers, and see how much more effective torque you are laying down.

 

[96dc2]

Louse, try the calculators on this site.

 

[adamones]

If a stock GS-R ran a 1/4mile with 15s would it be faster or equal to a stock GS-R with 16s? I was just wondering if bigger wheels actually help improve your speed, and if they do whats the best size for the fastest speed?

Thats my burning question. Im still a moron and I still dont get it

 

[96dc2]

I just answered that on page 1. Do you want top speed? Or a quick 1/4-mile time? I personally would run the smallest wheel that will clear the brakes so I can have more sidewall.

 

[Louse76]

So it seems that (if the tire measurements are actually accurate), going from a 205/50/15 to a 195/50/15 would give an extra 1.736% torque to the ground.