B.Money

Hey guys, I recently purchased some prodrive gc-07's and want to use them for DD and track duty (live very close to willow springs).

Now my specs are 17x7.5 +48 and 17x8.5 +54 and im wondering how much (if at all noticeable) offsets effect handling from the stock +55/+65 offsets?

I have my ap1 wheels still but plan on selling them due to room in the garage. I just dont want grip to suffer or handling characteristics changed drastically. I have also heard comments of these wheels made specifically for the s2000, but I dont see how that can be as they still need hubcentric rings.

Anyway can someone assure me handling wont be screwed up or anything? As of now I havnt even experimented with R-Comps, as of now I am running RE-01's

TIA guys!

alejo

that's not much of a difference, specially considering that you remain staggered.

B.Money

yeah Im still staggered on 225/255 tires. Do you think ill gain any grip with this setup? possible more understeer, because the offsets (rears are slightly lower offset than stock)

mikegarrison

Any difference due to wheel offsets is going to be so subtle that you will never be able to pick it out.

You probably are going to see a difference with the new wheels, but it will be due to the size of the wheels, not the offsets.

The exception would be if the offsets are screwed up and you have clearance issues.

Suspension

You should just look at the change in offset. You've moved the center of the contact patch (assuming 0 camber) 7mm out in the front and 9 mm out in the rear on each side. That is an increase in front track of 14mm and rear track of 18mm. Which is insignificant compared to the track width of ~1500 mm, on the order of a 1% increase. In other words, it won't change the characteristics of the car. No change in balance (over/understeer).

Increasing your track generally increases lateral grip capabilities by reducing total weight transfer, but in your case it's negligible. You'll probably feel more grip due to the wider tires than due to the change in track. I think those wheels are a great application for the s2000 and my RE01Rs have been awesome. Enjoy.

cthree

Here is a question...

Both my car and the car of my S2000 competitor were in the same shop at the same time. When loading my competitor's car on a trailer my fabricator noted a track width difference between the two cars at over 2" (about 2.5" by eye). What are the effects of this wider track on his car vs. mine?

B.Money

Thanks you guys! they look awesome! I just bolted them on and I drove them down the block they feel pretty much the same, maybe a little less steering response due to wider/newer tires.

Thanks again guys! you guys are great!

mikegarrison

Wider track should mean the weight is more evenly distributed in the corners. Not sure whether the 2 inches is significant, though.

Borbor

A few things I can think of:

a) Higher static roll center. We're talking thousandths or at best tenths of an inch here, since the track increase is only on the order of 1.6% per half of the car, so if you drew the suspension configuration out, it should raise it by a slight amount.

b) As suspension as said, increased lateral grip capabilites. Assuming Sam and you drive in similar style, that means theoretically he could have higher cornering speeds than you do. (lest not forget driver behaviour also factors in how the tires are loaded) Having said that, it'll need a bunch of variables to be the same as well; mainly suspension components and alignment, total overall weight of the car and cg height of both cars.

c) Scrub radius increase. Some people don't think this affects handling at all, for those in that school of thought, go drive a kart (not a rental) and then spend a few sessions adding and taking away spacers from the front spindle and I'm fairly certain you can feel the difference. Mainly, it's got to deal with the steering feedback, but a bunch of other things like weight jacking w/ steering input.

For those not familiar with terminology, the def'n of scrub radius is the intersection point on the ground between the steering rotation axis to the wheel centerline. Go take a look at the forums in fsae.com, I'm sure suspension can give you his piece on here about scrub as well seeing how he was part of a pretty good fsae program in Cornell Those guys have beaten the dead horse a few times over on this very topic and how it affects handling.

Suspension

Very good answer, Borbor, and you must be an FSAE vet of the same era as me to recognize my avatar.

Borbor covered all of the things that change with an increase in track, and I would say a) and b) have a negligible effect with this small of a track difference but c) could be felt if the stock scrub radius is small to begin with. It could lead to heavier steering (if no assit is used) and more feedback in to the steering wheel during braking.