A simple tire size question

Okay, after years of riding stock tires and rims, I am upgrading. I've learned a little about rims and tires thanks to this wonderful forum. But, I have a really dumb question. When dealing with tire sizes, which would give a more low profile look, a 205/40R17 or a 215/45R17? I know this is probably a bonehead question, but I have a very limited knowledge of tire sizes. If anyone has a picture of those particular sizes on a G, that would be helpful in my decision process (you see, I found some great tire/wheel packages, but I'm not quite sure what the tires that come with the package are going to look like on the rim). I'd hate to get a nice set of rims shipped to my door, with FAT 4x4 tires on them. To make it easier, my G is lowered roughly 2" front/back. So, there won't be any wheel well gap. So, should I go 205/40R17 or 215/45R17??? Thanks!!!!!!

I think you will have better luck fitting the 205 tire, as the 215 may be a tad wide, and you'll really have to worry about the offset, as it'll have to be right on to fit. I had 205-45-16's on my P10 and I didn't have any rubbing or anything, i still had some room on each side (not much though), i think a 215, in my application, would have been pushing it, especially if i went up in sidewall size too, like to 205-50, or 215-45... however, i'm not sure how the p11's are for wheel well size? Your car may differ quite a bit from mine?

Originally posted by G20Rob3
When dealing with tire sizes, which would give a more low profile look, a 205/40R17 or a 215/45R17?

Tire sizes are given in the format:

Width(MM)/Sidewall height percentage of Width/wheel size


So...

205/40/17 has a width of 205mm and 82mm profile (40% of 205)
215/45/17 has a width of 215mm and 96.75mm profile (45% of 215)


http://www.discounttiredirect.com/helpTireDimensions.html


I have noticed that the profile never appears to be what the formula says. For example my 225/40/18 have a "90mm" profile which is about 3.5" however if you look, it does not appear to be that big. I think it has to due w/ air pressure, weight of the car and the fact that the tire rounds over on the corner.

Rob,

You're looking at two very different tire sizes here. Generally, you either want a wider tire with a lower profile, or a narrower (relatively) tire with a higher profile. If you go with 215/45's you're getting a tire that's wider AND taller (not a good idea with a 2" drop, IMO). I recently bought new wheels and tires for my car and got 205/40-R17 Toyo's. However; i only bought that size because it's the size that came in the "package deal". Otherwise, i would have gotten 205/45-R17's instead. Take a look at Jason's wheel page (http://www.g20.net/mod_wheels.html) and you'll see why. 205/40's and 215/40's are smaller in diameter than the stock tires. 205/45's are almost exactly the same size, while 215/45's are larger diameter than stock. So, the tire you select will affect your gearing and speedometer/odometer error as well as the look of the car. Also, using a 45 series will look very similar but will give you just a *little* more sidewall to cushion your rim when you hit a pothole (which you will). As i said, i've got the 205/40's on my car (as do most of the people here) but if i had not been "forced" into that size by the package deal that i purchased, i'd have gotten the 205/45's instead.

BTW, just got my new wheels this morning. Haven't even mounted them yet. Hopefully i'll get them on tomorrow - at which point i'll start budgeting for springs and shocks. :-)

-Grant

b-boogie,

You are correct in explaining the tire format, however, you missed the key word: "aspect ratio". The number 40 or 45, as an example above, is known as the aspect ratio. You can learn about tire dimension and its characteristics at most tire sites.

I am getting new rim/wheel this Spring. I am looking at the 215/40/18 with around 40 to 45mm offset.

I just didnt want to get all technical... I was explaining how you figure the numbers. The link I posted from Discount Tires has pictures..


BTW with 18's on a P11 the 215/40 will be a little smaller than the stock diameter which is 24.2".

225/35/18 is a perfect match, but I went with 225/40/18's for a little added support. This was mainly because I first had 215/35/18's (rubber bands, lol) and ruined 2 wheels. I was gonna go w/ the 225/35 but figured I might as well get the added protection.

Next tires I get will be the 225/35's though. ;)