Non Staggered Setup Thoughts (Updated 8 Feb 2020)

Some S2000 owners, including myself, have gone to a setup where the front tyres are the same as the rears called the non staggered setup. This may seem a step towards increasing the high potential for snap oversteer as many S2000 owners have experienced yet based on my experience, it has delivered so much in gains that I would not look back to regular staggered setup, where front tyres are narrower than the rears, until I can find evidence that the staggered setup performs better.

Update: This is how the car looked when the non staggered Enkei wheels were fitted

Side profile

Front poke from the side

Rear poke from the side

Let's look at the S2000 setup in stock form. With 215/45/17 tyres up front and 245/40/17 tyres out in the rear, the feel I get is that the intial turn-in is lacking in grip. The result of this is that the driver tends to add more lock to get the car to turn and when the car finally responds, there is excessive steering lock and the tail of the car snaps around. This tendency remains even when camber angles are increased to give more grip to the fronts and it is my thought that this is wholly due to front tyres that are too skinny.

Update: There might be a tendency to overcook the front tyres over many laps during turn in as with the skinnier profile of the stock tyres, the tyre might have less ability to handle the heat built up.

When I shifted to a non staggered tyre setup with front tyres as wide as the rear, the turn in was excellent. Feedback did seem a little numb but you would pretty much know how much grip there was as the steering was still communicative. At higher speeds, due to the high amount of rear lift the S2000 generates along with the fact that I had fitted a large front splitter, the front gripped far more than the back and resulted in a rather white knuckled ride. This left me with doubts about how the non staggered setup had upset the natural balance of the car.

Update: The slightly "numb" feel might be due to the relatively thicker profile of the front tyre and sidewall stiffness of the tyre I was using at that time. In retrospec, the splitter seemed to be the main reason for oversteer at higher speeds and the lower speeds "oversteer" tendency could be handled by relatively less steering input than stock.
For those seeking a budget non staggered setup, 2 rear wheels of the AP2 might be used on the fronts with same size rear and front tyres. There might be clearance issues at full lock which can be solved with a spacer or with steering lock limiters.

I subsequently fitted a high mount GT wing to balance the tail of the car and the result was phenomenal. Not only did the rear lift get cancelled out, I also retained the excellent turn-in characteristics of the car. This was far more pronounced when I got to the track. When turning in, the car would simply grip and go and I had no need to add any excessive lock but was rather using far less steering lock than before which is easily seen as much more efficient. In the slower corners, I was able to turn in sharply and get the car to rotate (as the rear wing grip was far less due to lower speeds) while at higher speeds, the slight oversteer would change to slight understeer as the balance of grip shifted to the rear. Braking was also a much more stable affair with the increased stance of the car.

I was hampered by a leaking brake master pump, torn in half shifter bush, leaking clutch pump, overly understeering alignment & wrong tyre pressures at the latest track day I attended. This resulted in only a very slight improvement in my personal best laptimes which was a definite disappointment. However, I am confident that after the repairs, the car will be able to hit the benchmark times I have aided by the transformed characteristics of the car.

Even though it seems counter intuitive to conventional wisdom (you can't imagine how many "old birds" of the tracking scene scoffed my new setup) seeing how many performance cars have rear tyres much wider than the front, deeper analysis into racing cars seems to favour the non staggered setup. Many racing cars have front track & tyres as wide or wider than the front to aid their turn-in and front grip with the rear aero dynamics compensating for rear grip. Although its hard to tell on paper which is better, having experienced the difference on the road and track, I am definitely of the opinion that non staggered is the way to go for track-biased cars. The only caveat would be that the driver needs to be experienced enough to measure his steering inputs accordingly.

Update: Many years have transpired since I embarked on the non staggered setup and when I initially did so, the setup was viewed with apprehension and sometimes mocked. By now, it has become the de facto go to setup that owners see as necessary for best for the track. As they say, "Time will tell" and it has been clearly evidenced from tests. Any car can be made to be setup best for a staggered or non staggered setup but the generally easy to find setup plus the benefit of being able to cross rotate for even wear for the non staggered setup has clearly won over many owners.

Considerations on non staggered fitment are the following:
1. Rolling and pulling of the fenders are mostly necessary (there seems no point in my opinion to run tucked in offsets just for fender clearance when the increased track of lower offset will deliver great gains)
2. Camber requires to be to tuned to your driving style (it seems necessary to have a proper data to support better alignment to optimize the alignment)
3. Improved aero i.e. GT wing is necessary (you will be resetting the balance of the car and an adjustable efficient wing will go a long way to ensuring your setup is effective)
4. Some rubbing of fender liners and suspension cars will be experienced (this is an eventuality non staggered owners will have to accept)
5. Fender tab relocation and bumper trimming is necessary(again this is necessary to prevent rubbing of your tyres)

Update:
For 1. - Gains from a lower offset come with the trade off of a change of scrub radius which will change steering effort and some response of the steering. I would say its best for the owner to read a bit more on this to see if this is something they can accept which may change the driving feel for them.
The lack of wide choice of rims in high offset (the Enkei PF01SS is one of the few +60 wheels easily available unless you would like to spring big money for forged Rays wheels) says to me that doing rolling and pulling actually helps widen the choice available for wheel upgrades.
Plenty of people told me the Enkei RPF1 17x9 +45 offset fit easily with rolling and camber resulting in my choice to get them but I was pretty surprised to see the actual fitment on stock fenders with 255/40/17 AD08 tyres. Please stop saying they fit so easily!

Front view of front poke, clear enough to see how much they stick out

Front poke top view. Without modification you WILL mess the hell out of your front fender on a big compression on your suspension and ruin BOTH fender plus tyre.

Rear poke seen from the front. It doesn't seem all that much bit I think its harder to work the rear than it is the front from feedback from the body shop I went to.

Rear poke seen from the rear view. You might be able to make out that my rear fenders are already very slightly pulled and rolled but at that time I was still having rubbing on big dips in the road when the suspension compressed a lot. A more stiffly sprung suspension might be able to get away with less fender work. 

For 2, - Alignment is a beaten to death topic and there is an immense trove of information on recommended settings for staggered or non staggered setups. For performance oriented setups, getting help to properly set up the car saves you tons of guesswork and wasted trips to the track.
For 3. As earlier mentioned, I'd attribute the higher speed handling change to the splitter so the wing is primarily to balance that change. It is important to note that the design of the underbody of the S2000 generates a large amount of lift leading to rather sketchy handling at higher speed, apparently lifting the tail up. A smallish Type S size wing can help settle the tail quite nicely without significant drag penalty.

The ultimate caveat here for fitment of a non staggered setup is that owners who want the aesthetic appeal of the car maintained may be disappointed. To clear non staggered setups, the car may be raised slightly, may need body work, may have slightly wavy paint due to rolling & cutting, may have protuding tyres etc. Everyone chooses how they want their car to be and I think its important that owners know the impact of non staggered in the aesthetic sense before they embark on this journey. The track-crazy S2000 drivers wouldn't be too bothered by these sacrifices as the on-track performance would likely be sufficient to compensate.

Update: One further thought regarding the work required for the non staggered setup to pay off might be that the choice of brake upgrades would be wider and eliminating the need for spacers. The RPF1 in this offset will not fit a brake kit due to the inset spokes. The Enkei Racing GTC 01 I currently run has plenty of room for  big brake kit due to the way the spokes are designed.

I welcome any non staggered owners to discuss their setups openly or in private and hope my anecdotal thoughts are of use to any readers out there :)