tire question...
 

i have 255 55 18s and i was wondering if 245 40 18s would fit my rim?

Probably. What size is the rim?

18x9 or 18x10 idk.

the ones the 245 40 are on is 18x9

A 245/40/18 requires 8.0"-9.5" wide rims. OD is 25.71"

A 255/55/18 requires 7.0"-9.0" wide rims. OD is 29.04"

Big height difference.

http://www.1010tires.com/TireSizeCal...?action=submit

my rim with the 255 55 is a 18x9.5

the height will only throw off my speedo..no?

Assuming it is corect with the 255/55/18, yes, it will whack it pretty good.

At 60 mph it will read 67.7 mph
Speedometer Difference: 12.95% too fast

Might look funny too. Could also whack ABS and/or traction contol, if equipped.


Are you buying thses tires new or is this some deal on used tires?

well, my speedo is off as it is. at 50 im reading 60 lol

I concur with Scott. It seems that the tires you have on there are already off, so they dont seem to be correct.
What kind of car is this going on? And for a 9.5 inch rim, a 245 will look silly.

whats your stock size? take it from there and use the 1 up, + 10, - 10 formula.

Would you also need to be concerned with getting a good bead? the chart I referenced shows a 9.5 wide rim should have a 265/275 W tire.

Sliderule, I tend to look at the recommended rim widths for a given tire size. MRW can vary based on aspect ratio (40) as well as section width (245). For instance:

245/30/20 7.0-8.0
245/50/16 7.0-8.5
245/45/17 7.5-9.0
245/40/17 8.0-9.5

its on my durango..the tire it came with was 255 55 18

I'm, confused. What vehicle is getting the new tire size? What is the OE size on that vehicle?

idk oe size. the original rims r 15s but idk original size. it has american racing 18s

look in your door jambs for the oe tire size. then you can calculate what tire size you should have from there.


for example


195 75 14 > 205/65/15 > 215/55/16 > 225/45/17 and so on

use the +10, 10 , +1 formula
every inch you go up in rim size increase the width by 10 and drop the profile by 10.

255/55-18 sounds a little small for a durango.
Depending on the year, Durango has a BUNCH of different sizes from 235/75-15 to 31x10.5x15. The newwer ones are pretty common but big.
I want to say that 255/60-18 is probably the size you are looking for. 265/70-15 is a common size as well for the older ones after they stopped putting the 31's on it.