Tire & Rim Sizes ??

[Noell]

hey - i wanted to know what was the safest size tire and rim to get on a 2002 mercury cougar v-6 6-cyl. ... what is the largest you can go ? i said something to my dad and he said " you cant do 18 " !! its too big !! " so can you all help me out ?? thanx !

[YogsVR4]

Yes - you can have 18s on there though I think some nice 17s would look better. The width will be 7 to 7.5 inches so you'll have

18s with 215/45 or 17s with 215/50

take some pics when you have the new tires

[Cy@tirerack]

215/45-18 & 225/40-18 would work fine.

[YogsVR4]

Originally posted by Cy@tirerack
215/45-18 & 225/40-18 would work fine.

the 225s would be fine but wouldn't the 40s understate the cars speed?

[Route666]

The 215s have a bigger overall diametre, so these would understate the speed more than the 40s

[Cy@tirerack]

Here the possible sizes for your car along with overall diameters:

38550 205/60-15 24.7 45750 225/50-16 24.9
39050 215/60-15 25.2 49500 215/45-17 24.6
44950 205/55-16 24.9 49650 225/45-17 25.0
45300 215/50-16 24.5 53400 215/40-18 24.7
225/40-18 25.1

You can calcute the overestimation or underestimation of speed by calculating the percentage difference and remembering that smaller tires cause your speedo to overestimate speed and bigger tires cause your speed to underestimate your speed.

So 215/40-18 would cause no speedo error. If you ran 225/40-18 your speedo would underestimate your speed by 1.6%.

In general as long as you stay within a 3% margin and the tire has sufficient load capacity (all the above do), you'll be fine.