Ride height for 17" wheels???!!

hkspwrsche · 10-31-2004, 09:23 AM

IS the rough fender to ground measurement (for ride height) for the 17" wheels different than it is for stock 16" fuchs?? I dont have both sets of wheels to see if the diameter is different but I want to make sure...I might be buying back my old 17's!

Or to put it another way are the 17" cup wheels WITH tires larger diameter or just a plus one size from the 16" factory fuchs?

Joehand1 · Joehand1's Garage

I went from 15 in Fuchs with Yokahomas to 17 in cups with SO3s, no difference in total diameter, no ride adjustment was needed.

hkspwrsche · 10-31-2004, 09:56 AM

I think I remember the 17's being about 27" in diameter or close to that.. I wouldnt think the ride height would need to be adjusted but, I would think it would change the measurement of fender to ground.

rdane · rdane's Garage

Depends on the tire. My 16"s are almost a .50" bigger in diameter than my 17" tires, same brand and model of tire. That makes a difference in .25" in ride height. Yours may be more or less.

What I did notice driving n and out of the drive way was a new front spoiler drags with the 16"s and didn't with the 17"s.

Yellowbird RS · 10-31-2004, 10:17 AM

use the tire calculator see the diameter.

Jack Olsen · 10-31-2004, 02:27 PM

Wheel size and the diameter of a tire have very little to do with each other. Tire size has everything to do with the dimeter of a tire. Use a tire-size calculator to see what the change is going to be between one tire to another.

Common myths are that larger diameter wheels will adversely affect the car's ride height, gearing or handling -- or that larger diameter wheels will increase unsprung weight. Often, it's the opposite.

Bill Verburg · Bill Verburg's Garage

Here's an example of what they are talking about
285/30x18 on the left 225/50x16(oem SC/Carrera fitment) on the right

Jack Olsen · 10-31-2004, 03:25 PM

The difference between a 225/50x16 and a 225/45x17 is only a tenth of an inch. And if you increase your width, a 245/40x17 is about a 1/4 inch smaller than the 225/50x16.

hkspwrsche · 10-31-2004, 07:33 PM

Thanks jack. Thats what I was trying to figure out without the tire sizes in front of me!
I had someone tell me that the 17" set up would make the car look taller??.. I couldnt figure out how that would happen because it should be a plus one size increase where the aspect ratio would remain the same.

Wil Ferch · 11-02-2004, 09:21 AM

All of Porsche's factory fitment tires were approx 25" rolling diameter...from the earliest 165 section 15's....to 185/70-15's.... 205/55-16's to 225/50-16's...etc. All just under/at 25". Just do the math.

Wil

Roamer · 11-02-2004, 10:11 AM

25.4" is the outside tire diameter found on most 911's (depending upon the tire).

Wil Ferch · 11-02-2004, 11:34 AM

My calcs say 24.88....but we're splitting hairs....certainly not 26 or 27.

Wil

Bill Verburg · Bill Verburg's Garage

Roger Kraus Tires gives the following
185/70R15 25.71" tall 7.30' crosssection My old Bridgestone manual gives 25.5" & 7.2"

215/60x15 as 25.3" & 8.2"

Thshortest ever used in the back in the semi modern ers was the 225/50x15 @ 24" and 8.9"

Wil Ferch · 11-03-2004, 05:35 AM

205/55-26:
Section width 205mm= 8.07"
{8.07(0.55) x 2} + 16 = 24.877"

Same with 225/50-16:
Section width 225mm=8.86"
{8.86(0.50) x 2} +16 = 24.858"

185/70-15:
Section width 185mm= 7.28"
{7.28(0.70) x 2 } +15 = 25.2"

These seem to agree with tire manufacturer's specs too...again, we're splitting hairs as the answer is about 25" ( +/-)....and we never got close to high 26-27".

Wil

89911 · 11-03-2004, 05:50 AM

My car with 17" sits noticable higher then with the 16"s, perhaps an inch. Curbs and speedbumps are noticable more a nuisance with the 16". Most if this is due to the front tires. The Fuchs have a very low profile 225/40/16 for clearance. The 17" run a 235/40/17. Since I change tire sizes frequently, I don't change the height between the two. Find a happy medium and set it there.