I just realized the previous owner had put the wrong size on my other car.
 

Instead of 255/40-17, he put 255/45-17.
I know some of you run 245/45-17 or those who wanted "beefier" tires
I'm buying tires soon, how would 1 inch less of tire change my ride? Ride harsher? Tire Wear wise?

I always wondered why the car looks lowered... Free 1 in" drop ftw & no wonder the speedo's been off by a lot... =_=

I think the 45 would be taller not shorter.

Yea which is why it has a 0.5" "drop" now

Ahh after you got new rubber. Sorry it confused me

I like to downsize tires, and put 225/40r18 instead of 225/45r18 which gave a 25 inch diameter instead of 26 inch.

Since it's a 07 6 speed auto it helps pull out of slow corners on the track.

Even though my car was "new" the dealer put 7.5 x 18 GF-1 Enkei's so I'm going to put 215/40r18 Michelin PSS on next time.

I use scangauge for calibrated speedo, and car hits governor at 117 instead of 125.

also, I might loose 1mpg, but the ride is .5 inch lower and I like it.

I'm at 42# wheel weight instead of stock 48# and next tire will get it into 39-40# area.

The only positive reason to downsize tire diameter noticeably beyond factory size is for gearing. This applies to mostly autox applications. Doing it for a better "ride" and "lower" car height makes as much sense as cutting off the soles of your shoes.

I think the 255/45/17 would be the better choice for a street driven car, as it's closer to the stock size. Also, while the 255/40 might be 1" shorter overall, the center only lowers 1/2 that, so you'll only get a 1/2" lowering, with the other 1/2" showing up as a bigger tire to fender gap, meaning if you wanted to minimize that gap, you'd have to lower the car that much more, making it that much more likely to scrape on driveways, speed bumps and the like.

I use 255/40/17 for my track tires for the gearing and lowering advantages, but am planning to stick to stock height for the street.

If you AutoX, having a smaller width tire (as mentioned) will help with the tire being able to roll faster in turns - that is the only reason.

You are getting more grip due to the bigger sized tire. 255 > 245 will NOT raise the car, that is the width.

If you are messing with the second number (tread height) from 45 > 40, than yes, you will go down, not up. A hire number, will increase in higher diameter for the tire.

Actually, if you go from, say, a 245/45/17 to a 255/45/17, then it does get taller. The second number represents sidewall height as a percentage of tread width, so 45% of 255mm is taller than 45% of 245mm.

Too tired ignore me