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Old 10-24-2013, 02:17 PM   #55 (permalink)
aardvarcus
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Quote:
Originally Posted by arudlang View Post
I was just looking at my 2011 CRZ and trying to figure out how tall I could go with new tires, not so much for efficiency but its getting to be winter in MN and I want to buy the tallest snow tires that will fit. 205/65R16 sounded perfect on paper but when I got to looking under my front fenders I though "no way those will clear the bottom plate of the coil spring!" (sorry I don't know exactly what that base is called where the bottom of the coil on the strut sits).

It looks like there's only about a half inch of possible clearance and that's with my tires wore wayyyy down (less than 1/16th tread remaining). So how in the world did you fit 2 inch taller 205/65 ??? Am I missing something that this won't be an issue with my car?

I hope the OP still watches this thread....
I am not the original poster but you are quoting me about the 205/65R16s that I used on a Toyota Celica, so I will tell you that before I bought those tires I did extensive measuring up under the car, and checked my clearances to everything. I am not familiar with your car so you will have to measure it yourself to see what you can fit, which it looks like you have done.

Remember that upsizing the diameter from 24” to 26.5” only increases the radius by 1.25”, so I had to check that I had 1.25 inches everywhere. You have to check it with the wheels straight, at half lock and full lock both directions. This step is very important, don’t just check it with the wheels straight! Also don’t forget suspension travel.

I had very little clearance to my strut tower coil spring base, but since that moved with the tire on compression that did not matter much, as long as I had something I was good. Your suspension setup may be different so you will have to make your own judgment on that. I had to remove my plastic wheel well liners to fit the tires under the car. The funny thing is that my limiting factor of what I could run was more based off of the width of the tire combined with the offset of the wheel, which would move the tire forwards and backwards as you turned the wheel.

Oh, and as an update to my previous post I am no longer running the 205/65R16s. When the fronts were over halfway gone I went back with the biggest Michelin Energy Savers I could fit on 15” Prius wheels. I still get part of the gearing advantages with less of the disadvantages associated with running right on the edge of what will fit. My old ones were 205/65R16’s at 26.5” or 10% over, and I moved to 195/65R15’s which are 25” or 4% over. With the old ones I had issues with accidentally squealing the tires taking off which rapidly wore them down, the tires were hard on my clutch to feather out the clutch and not squeak them, the tires would hit the fender wells on a hard bump, the big wheels and big tires were heavy, etcetera.

The funny thing is that my MPGs roughly stayed the same or maybe went down 0.5MPG so it was between a 0-1.3% loss in MPG for much better drivability. It is very hard to tell differences that small just using weekly tanks without A-B testing. I gained efficiency from the weight (minus 40lbs rotating weight)/aero savings(3/4” lower car, new aerodynamic wheels) , but lost efficiency on running higher RPMs (+200 RPMs). I can’t complain about the old tires through, I saved enough fuel when I had them to more than offset the purchase price.

Note that I still am on 4% oversized tires from stock and still a believer in them until I can regear my transaxle, but my suggestion is to not run the absolute biggest thing you can cram under there, leave yourself some wiggle room and consider the other factors that your tire selection impacts, such as rim selection, weight, ride height, etcetera.
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