doc stang

so i am staging suspension choices for my 08 bullitt.
plan is a daily driver with 4-5 HPDE's this year, and hopefully 8-10 next year, and then on to time-trialing.

i will probably be doing sway bars, springs (linear rate ~1-1..5" lowering), d-specs (or konis), camber stuff, etc.

i foresee eventually getting some nice lightweight 17x9's and running some 275x40 18s on all corners. these would be for track duty only.
being a bullitt, i intend to stick with the stock 18x8.5 "BULLITT" bullitts, since they are special to the car.

MY QUESTION IS: . . .
will I incur any detrimental effect from changing between the 18" rims (and whatever tires for daily driving), vs changing to the track shoes described above?

i would assume the car will be a little lower on the track shoes, which would seem to be a good thing.

if i optimize the handling setup for the daily driver ride height (tire wheel combo being the only change) will this leave me wanting at the track?
or if i optimize the handling setup for teh lower track wheels/tires, will ths leave me suffering on the street?
do i set things up at the midpoint between?

does the wheel tire combo /diameter have any bearing on any of teh settings on the rest of the suspension set up (meaning i could change wheels/tires w/o any difference).
thanks,
doc

Jazzer The Cat

You will not have an issue changing all the tires/rims for track use (maybe speedo if you have differing diameters). The only issue would possibly be wheel-well clearance if you set up car for DD with smaller tires or different off-sets. If tires are alot smaller/larger, I am sure there would be some difference, but someone else will have to chime in on that.

If you set the car up for DD, to some degree it will leave you wanting at the track, as you may want more aggressive camber or possibly lower, or stiffer springs/shocks. My thinking would be if it is NORMALLY a DD car, you will be more likely to be better driver on the track if you leave it as you do when on the street. For example: I have quite the audio system in my car. Running two 26 LB subs in very back corners of trunk, lots of amps and such. I have a spare tire as well. When I go to the track, I will leave it exactly as it is. This way, I will be used to how it reacts in turns, and how much I can push it before it brakes loose. This would certainly NOT be the best optionif I wanted to get all I can out of my car, but will be predictable, and is MUCH more important to me.

So I will sum it up in this way. If you are 75% DD and 25% track, I recommend leaving it 100% unchanged.If you are the reverse, set it up for track, but tolerable on the street. Maybe some more aggressive/softer tires for track-only use.

This is just my opinion, as others may disagree, but what I would do

Jazzer

Argonaut

I'm running 18x9 daily and 17x9 for track and AX. It doesn't change your suspension geometry but it does lower the car an inch (255/40/17), with the Eibach springs it is very low and really not suitable for city driving, I have driven to events with the 17s on an had no problems. The other issue is it throws off your speedo. And one more problem, with the 17s on I can't get a floor jack under the front, side or back...have to drive up on a ramp and then jack it up.

jayel579

275/40-17s are a great tire size for track use. I run them on my track wheels (17x8). It is the stock tire size on a C4 corvette so tire choices are abundant and tend to be less expensive compared to an 18" performance tire.

Jazzer The Cat

Actually, 1/2"

Jazzer

Argonaut

You are correct that the diff in ride height between an 18" rim and a 17" rim is 1/2 inch. I was referring to the overall diameter and therefore radius however. My 18s have 255/45 rubber on them, overall diameter = 27.03". The 17s have 255/40 tires, overall diameter = 25.03. Difference in ride height = 27.03 - 25.03/2 = 1". Sorry if I wasn't clear.

Jazzer The Cat

I almost asked if you were running a lower profile on 17"s, but was just givin' ya a hard time [8D]

Sounds good.

Jazzer