I guess most of you thought a pic was here, but not just yet. What i forgot to realize is that wont my rear ratio change, since my original tire size 245/50ZR16 is going to 295/40ZR18. I originally have 3.42 out back, but will going from 50 to 40 help retain the 3.42 ratio or do i have to go lower?

 

285/35 or 245/40 if you want to be as close as possible to the stock diameter

 

I had no idea that the width of the tire would affect the ratio. I thought it was only the diameter of the rim and tire.

 

youd be going from 25.6 inches around to 27.3, so your speedo would definetely be off (with the 295/40's)

a 285/35/18 would would you at 26.9inches so it wouldnt be noticeable.

a 295/35/18 would be 26.1 and would probably be bearable too.

if you go with a 35 series tire then make sure youre careful if you drive it on the streets

 

I know this is a stupid question, and its because of the narrow sidewall, but why? What are the negative side effects of running a narrow wall?

 

i went from the stock size of 245/50/16 all round to 265/35/18 on back and 225/40/18 up front..

i dont notice my speedometer any different..

the reason with a smaller sidewall you have to take more care is because usually when you have a small side wall the actual width of the tire isnt that wide and wont take most of the impact..

example

245/50/16 is for instance this wide /......................./
and this is the side wall _


............................... _


while my 265/35/18 is this wide /.............................../
and this for a side wall _
..............................._



as you can see (hopefully ) that you have more padding with more of a sidewall to protect you rim..

also find attatched my front rim and tire.. 225/40/18 maybe can show you there stock tire (the 245/50/16)

iroc2nv

 

narrow sidewall makes it easier to mess up the tire or damage the rim. especially if you go with a rim that has a deep dish.

 

http://www.juric.org/mopar/tools/tirecalc.php

try this tool... it rocks

 

I recommend re-inforced sidewalls if you go 35 series or lower. Like these guys said, if the sidewall is too small and not re-inforced its possible for the rim to be damaged if you hit a pothole. I'm running re-inforced 275/35/18 tires in the rear (245/40/18 front) and my few run-ins with potholes have resulted in no damage. Hope this helps.