Which size tire and rims should I get?

Question

I have a '99 cougar v6 2.5L atx with:
rims- stock 15's
tires- stock 205/60


I am thinkin about upgrading to 16" or 17" tires/rims, but I dont want to mess the speedometer up by drastically changing the wheel circumfrence.

Here are a few options I've seen for 16/17" rims:
16/205/55
16/215/50
16/225/45
16/225/50
17/205/40
17/225/45


Should I go for lower profile or wider tire or get both and not worry about the speedometer?

Answer 1

You will know how to figure speedometer error / tire sizes bu visiting tirerack.com. Open any brand tire they carry. Then open specs. On that page to the far right you will see a column that says "RPM". This means in tire language revolutions per mile.

Check your exact tire size and jot the RPM of your tire. Now comes the fun. As tires get larger you can stay very close to your original RPM by going to a larger tire with a smaller aspect ratio. For instance: check a 225 - 50 tire and see how close the RPM's are compared to the originals. The larger the tire diameter you will need to keep reducing aspect ratios to keep the speedometer correct. It's OK to cheat a little by choosing a tire that rolls 15 - 20 feet less rpm's per mile as it will not wreck your reading on the spedo. Anything more than that your speedometer is out the window. Have fun with this site!

Answer 2

largest size rims are 18 by 8

Answer 3

Go for it, not much can affect your speedometer trust me my husband changes from 16" rims to 20" rims and its always the same. And it all depends on how you want the car to look. Personally With a cougar Id go with low profile wide tires and make it look mean. Now Thats HOTTTT.

Answer 4

I suggest getting the ones you want to have on the car (that fit the wheel well) and then go talk to a cop and get it tested.
(I spoke with my local chief of police and he let me borrow the radar gun when I was dialing in a transmission)
When you know how much of a difference you have, you can then decide if it is acceptable or not.
If not, go to your local trans shop and explain what you have done and ask for the speedo bullet that will correct the speedometer. (generally one size up or down)
I believe I spent 5.00 for the correct bullet when I was working on my last Chevy.

Answer 5

Well, by doing calculations, I have determined your factory tire diameter to be:
24.69 inches

(Option) [dia in in.] {difference (inches) from stock}
(205/55R16) [24.88] {0.19}
(215/50R16) [24.46] {0.23}
(225/45R16) [23.97] {0.72}
(225/50R16) [24.86] {0.17}
(205/40R17) [23.46] {1.23}
(225/45R17) [24.97] {0.28}


Obviously your best bet is going to be the fourth choice, but any of them except for the third and fifth choices should have a negligible impact on your speedometer.

Hope this helps.

Answer 6

What you should concern is for the maneuverability, if you change the from-fabric system this can make the car more unstable, perhaps can affect the front and rear train. Also you'll have to make some modifications to avoid hit the fenders and the inner part of the car in the fron and rear. Different kind of shock absorbers and spacers.

Answer 7

Low profile looks nice on rims, but wide tires slow you down and suck if it snows..

Answer 8

go to the tirerack.com they will have a plus size chart that will show you what size tires will work and not change your speedo reading

Answer 9

step up to 19's ....low profile ...19x 7, 19x 8....tires...255 up front...295 in the rear....40 series

Answer 10

contact your cougar dealer for information or use this link i am sending you.www.cougardb.com/car.php?id=jaged