I already did a search...found nothing

I already know from previous knowledge that if you have smaller rims it will help you signifcantly with acceleration. What about top speed??? The way I see it bigger rims equals bigger diameter which equal less revolutions per X amount of distance ex. 15's > amount of rpm's than 17's over a X amount of distance which i assume is less for the transmission which equals longer spining the gears longer which equals GREATER TOP SPEED???? please correct me if im wrong... this is just some theory i put together in my head and insight or info would help...

Oh, BTW what about TIRES i mean a 16 with 205/16/50 has a greater diameter than 205/16/45, just some more stuff to think about, but LETS ASSUME ALL THE TIRES IN THE EXAMPLE ABOVE ARE EQUAL IN SIDE WALL MESURMENTS.


Modified by mrmonk at 4:20 PM 1/30/2004

 

Bigger diameter rims with lower profile tires, IF the overall outside diameter of the tire tread is the same, shouldn't do anything to your top speed. That'll influence your acceleration just because they'll weigh more or less than your stock wheels & tires.

If you go to a different overall tread diameter it's pretty much like having a different final drive ratio.

It's kinda misleading to say the sidewall profile is the same. What's important is whether the overall tread diameter is the same.

A less-important thing is whether a smaller rim with taller sidewall can have better traction during launch.(?) Is this why they're used for drag racing?? (I don't know.)

 

you have it backwards buddy. 45% is going to have smaller diameter than 50%.
Everything jimblake has said is dead on. just remember tire width also plays a factor, though minor.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrmonk &raquo;</TD></TR><TR><TD CLASS="quote">
Oh, BTW what about TIRES i mean a 16 with 205/16/45 has a greater diameter than 205/16/50, just some more stuff to think about, but LETS ASSUME ALL THE TIRES IN THE EXAMPLE ABOVE ARE EQUAL IN SIDE WALL MESURMENTS.</TD></TR></TABLE>

 

LOL, YOU GUYS DONT GET THE POINT and i dont have it backwords... im trying to make an example here not compare what people have on thier cars ofcourse a person with a bigger rim is going to have a smaller side wall which makes the overall diameter the same regardless of whether you have 15's 16's or 17's.....

IM trying to say if you have

IN SIZE 15's w/tires &lt; 16's w/tires &lt;17's w/tires

what are the performance gains losses

and will a bigger overall diameter increase ones top speed, WHEW** thankyou.

 

Weighted was mentioned if you payed attention, you can't speak for all 16" wheels and 17" wheels because they also have depth to them and different materials. Which counter in for weight differences even with a bunch of wheels that are 16".

I think they're too many factors to base it down to one working universal formula. This is why **** cost too much.

 

So in theory, I understand what your saying about bigger wheels covering more distance per every 360 degree rotation. However, weight could factor in the top speed being limited compared to the light weight 15" spoon wheel. Or with enough power would you even have to worry about weight when compared to top speed? I don't even think my car pushes enough power for me to redline in 5th gear. So, I don't really think I could put 17"s on my car and try this, I don't think it would make much of a difference.

 

I think you're looking for a quick answer, but it's more complicated than that.

Well, outside of the terminology being backwards... (there's no such thing as a 205/16/50?)

Yes, 205/50-16 does have a bigger overall diameter than a 205/45-16. The 205/50-16 should be heavier than the 205/45-16. Unless you're talking about 2 different brands/models of tire.

The bigger overall diameter will act just like a slightly higher gear ratio, which may or may not increase your top speed. If top speed is limited by a speed limiter, then you'll be going faster even though your speedometer says the same thing.

If it's drag limited, then the different gearing will put you at a lower rpm, where you don't have as much power. So then it'll probably hurt your top speed. Besides the taller tire will raise the car slightly, which should increase your aero drag.

Even for acceleration it isn't clear. Smaller tread diameter gives you better acceleration at any specific rpm point, but it'll make you shift earlier, so that part can work against you depending on your shift point. You'll shift at the same rpm but you'll be shifting at lower true road speed.

Then there's differences in traction during launch... I really don't know much about the pros & cons of that.

 

SO FAR NON OF YOU HAVE ANSWERED MY QUESTION......


MORE POSTS PLZ!!!!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrmonk &raquo;</TD></TR><TR><TD CLASS="quote">and will a bigger overall diameter increase ones top speed</TD></TR></TABLE>

Yes. A larger overall diameter will create a larger overall tire circumference, and therfore will make your overall gearing taller. Thus, the top speed (gear limited) of the vehicle will go up a bit.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrmonk &raquo;</TD></TR><TR><TD CLASS="quote">
what are the performance gains losses

and will a bigger overall diameter increase ones top speed, WHEW** thankyou.
</TD></TR></TABLE>

It is unlikely that larger diameter tires would increase your top speed because Integra's are not gearing limited in 5th (we're limited by HP and aerodynamic drag). If you had an integra powerful enough to redline in 5th than yes, your top speed would be increased.

If your sidewall measurements on all 3 sizes are equal (which is a silly way to compare them) than you will see big differences in performance. A 195/55/15 vs a 205/55/17 in an acceleration test would leave the 17" equipped car with a serious gearing disadvantage. Top speed wouldn't matter because that car would be lucky to make it halfway through 5th gear.

Smaller will always be better for rimsize. Take a look at championship level autocross or Honda Challenge track cars as an example. 14's and 15's are what the smart guys run.

Cheers,
Sean

 

How does the width of a tire effect gearing? i.e.-205-225?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JunIntegra &raquo;</TD></TR><TR><TD CLASS="quote">How does the width of a tire effect gearing? i.e.-205-225?</TD></TR></TABLE>

A 225/50 tire will have larger sidewalls as opposed to a 205/50 tire. Therefore, the tire will have a larger circumference, and the car will end up with a taller final gear ratio.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JunIntegra &raquo;</TD></TR><TR><TD CLASS="quote">How does the width of a tire effect gearing? i.e.-205-225?</TD></TR></TABLE>It doesn't, exactly. It's hard to find a different width that's EXACTLY the same diameter, and it's the difference in diameter that changes 'gearing'.

205/50 and 225/45 are pretty close...

 

Weight in itself is not an issue -- the LOCATION of the weight in the wheel is. Wheels with a lot of weight towards the outside are a bad idea. Think of a wheel as a lever -- putting weight on the end of the lever makes it harder to swing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheGSRGuy &raquo;</TD></TR><TR><TD CLASS="quote">Weight in itself is not an issue -- the LOCATION of the weight in the wheel is. Wheels with a lot of weight towards the outside are a bad idea. Think of a wheel as a lever -- putting weight on the end of the lever makes it harder to swing.</TD></TR></TABLE>

Yes, he has it right there.

The weight of the wheel and the size doesn't matter THAT much. It's where the weight is placed that matters. If you compare a 20lb 15inch rim versus a 10lb 18 inch rim, what do you think will be faster? Truth is....it's hard to find out unless you do some serious testing in controlled situations.

The larger the diameter, the larger the moment of inertia (the force required to start spinning the wheel). The smaller the diameter, the smaller the moment of inertia, making it easier to start spinning the wheel.

Then again, the weight comes into play as well. If it's a heavy small wheel, the moment of inertia is smaller, but is still affected by the weight somewhat. If it's a light large wheel, the moment of inertia is different as well. There is a happy medium in there somewhere between weight and size.

That's why pro drag racers spend so much time figuring out what slick size to use and what rim size to use for a certain horsepower application. It's a science.

In a simple real world situation, you can just say that a lighter 15 inch wheel will yield better acceleration than something larger. A large diameter wheel will yield a slightly higher top speed.

Look into what one poster said about the final drive.

 

If anyone wants to learn more, read about 'moment of inertia'.