what are the advantages/disadvantages of bigger/smaller tire

[DSC]

I was wondering what the advantage/disadvantages were to haveing 18" rims vs 16" rims (assume no weight difference) and larger tires like 60 vs 50

(Edited by DSC at 6:25 pm on Jan. 23, 2002)

[White240sx]

Bigger wheel, less sidewall (45, 40, 35), better response (stretching the tire will do this too). Some would argue that it looks better too, but I would have to go the other way. Big tread width (225, 245, 275) is for traction, during launches and cornering laterally.

[Nismos14]

a 60 as apposed to 50 can cause more flex in hard cornering.... if u take a rim that is 18x8 a 235-245 width with about 45-50 sidewall would be best... if the sidewall is 60 then it would be better to get 225's so that the side wall is stretched a  bit for better cornering the disadvantage would be less tread touching the ground..... so thats part of it......

[LanceS13]

Do you know how absolutely huge a 225/60/18 tire is?  

Larger rims have more mass towards their outside.  More metal as opposed to more rubber and air.  The farther that mass is out on the wheel, the farther it has to go per rotation, and the harder it is to turn...thus it robs power.  Swing a yo-yo on 3 inches of its string in a circle; now swing it with 3 feet of string...same mass, but which one's easier to revolve?  

Larger rims allow for lower profile tires, which have less sidewall flex; thus causing more responsive handling.  However, tire sidewall compound stiffness can have just as much if not more to do with sidewall flex than the height of the sidewall.

Larger rims allow for huge rotors and calipers.  But cars that need massive brakes likely have ample power to turn the bigger reciprocating mass.

Sidewall stiffness somewhat determines how wide a tire can be.  A really stiff sidewalled R tire might can run 245 width with minimal flex and larger contact patch, whereas a tamer--more comfortable street tire's softer sidewall might limit it to 225 before sidewall flex begins to negate the added contact patch.

[DSC]

Good illustration lance.  Do you think 1" (total of 4" i guess...) in rim size would make much of a difference?

[LanceS13]

It depends on how heavy that 1&quot; is. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>
But in most cases, +1 wheel size and appropriate performance tires is one of the best things you can do for handling performance. &nbsp;I wouldn't go any bigger than 17's for sure. &nbsp;Light 16's with good tires would be best. &nbsp;But 17's would be fine...they'll look better too.

[chickenmanq]

Don't forget, you're screwing with gear ratios. &nbsp;Any time you increase your tire size, you are altering your gear ratio for the worse. &nbsp;Change in RPM band and less torque, more feathering of the clutch to start off.

Say you have a 225/60R18 wheel. &nbsp;That's 28.62 inches tall. &nbsp;Say your stock tire height is a 215/65/R15. &nbsp;That's an even 26 inches. &nbsp;I'm guessing these for illustration. &nbsp;So you've changed your tire size by 2.62 inches. &nbsp;Big deal? &nbsp;Yeah, major big deal. &nbsp;Say your current gear ratio is 3.70. &nbsp;With that change your effective ratio is 3.36. &nbsp;Big loss of torque.

Here's a formula to convert tire size to inches. &nbsp;Take the first number (width in mm) 225, move the decimal place over one so it's 22.5. &nbsp;(Converting to centimeters)Divide by 2.54 to give you inches. &nbsp;(8.85 inches) &nbsp;Take this number, and multiply by your aspect ratio. &nbsp;Second number. &nbsp;225 &lt;b&gt;65&lt;/b&gt;R15 &nbsp;8.85 x 5.75 inches, but you have two sidewall heights. &nbsp;(Another name for aspect ratio.) &nbsp;By the way, the aspect ratio is a percentage of your tire width. &nbsp;(225)

So multiply 5.75 by two, to account for the top and bottom sidewall. &nbsp;That's 11.51. &nbsp;Add this to the last number, rim height. &nbsp;15 + 11.51 = 26.51.

<a href="http://www.4lo.com" target='_blank'>http://www.4lo.com</a> has a gear calculation table if you're curious.


(Edited by chickenmanq at 10:37 pm on Jan. 23, 2002)

[LanceS13]

That's if you change the overall height of the tire. &nbsp;I think he means running larger rims with shorter sidewall tires to get correct overall height.

[chickenmanq]

Ahhhhh. &nbsp;Gotcha.

[BlankFlip]

i'm gonna have a shorter sidewall on my rear tires n more on the front.

[240racer]

BlankFlip, why do you want to run different sidewall heights? &nbsp;Also, White240sx what do you mean by stretching the tire, running one that is narrower then the rim?
thanks - Adam

[my240likenoother]

ok lets see
when you get a wider tire yor side wall will increase
you will not be able to fit a 225/50 or 60/18 on a 240
my 225/40/18 stand 25&quot; from the ground to the top of the tire
a 215/17/40 is the same size as the stock witch will not change the gear ratio and this will give you that shorter side wall wich you want and have a little flex for a decent hole shot of the line
i think that a 35 is too small and there is not enough flex in that side wall plus the ride will be rougher

[BlankFlip]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from 240racer on 6:50 pm on Jan. 24, 2002
BlankFlip, why do you want to run different sidewall heights? Also, White240sx what do you mean by stretching the tire, running one that is narrower then the rim?
thanks - Adam
</td></tr></table><span id='postcolor'>

fit my car better n for better handling in the rear, should be funner driving too <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>.

[Cam]

Here's a wheel/tire dimension calc if anyone has use for it:

http://www.mr2.com/FORMS/tire.html

Of course, it doesn't mean a certain size tire will physically fit on your car...