Deviating from SVTPP Configuration

[Madlock]

One thing I've learned is that the SVTPP is EXACTLY what Ford meant it to be - which is NOT what most dealers and buyers have turned it into.

 

Ford envisioned a 20% "take" rate - as a nicely-bundled track-oriented wheel/tire and suspension package - which only really delivers full value for anybody who plans to drive the car as-purchased. With the first change to wheels, tires or springs, you've pretty-much undone everything the SVTPP exists to provide.

 

But Ford DIDN'T count on dealers not understanding the difference (or caring) - or wanting to be stuck with the only car in its region that didn't have every box ticked on the order screen. They ALSO didn't count on people liking the look of the wheels and stripes to such an extent that many chose the SVTPP, for all intents and purposes, as a premium appearance package - or with visions of Barrett-Jackson in mind.

 

Here's MY dilemma.

 

I like the SVTPP just fine - and I've actually come to really appreciate how good the F1 G: 2s can be on a track. But I'm still trying to come-up with a solution for everyday driving - based either upon a second set of the staggered SVTPP wheels I've landed or a complete set of their 19 x 10 Ford Racing counterparts.

 

One of the most difficult aspects of choosing a different tire is sizing - because 285/35-20 and a 28" diameter is such an oddball reference point. On the other hand, almost every good performance tire comes in 285/35-19 - or even 285/30-20 both of which comes with more than its own share of inherent advantages, like a narrower profile for better handling or taking full advantage of the SVTPP's 3.73 gearing.

 

Where I get stuck is trying to weigh the impact upon rake and balance - because the SVTPP (Coupe) springs lower the car by 11mm in front and 8mm in the rear - but not without ALSO taking into account the fact that the larger rear tire elevates the rear axle by nearly ½". Unless I'm looking at things bassackwards, chopping ½" out from under the back-end may introduce negative effects I might not want.

 

On a baseline GT500 (or GT), the suspension actually takes into consideration a slightly larger front tire (than rear). Despite the perfunctory setup the SVTPP may be, it's also a pretty elegant balance between track aggression and everyday driving comfort, and I'd hate to inadvertently muck-up what Ford's SVT folks have bothered to put together now that Mustangs drive like Ford has actually taken them to a track or two before unleashing them upon the market. I'd be far LESS concerned about elevating the rear axle a smidgen than lowering it.

 

An obvious solution would be to simply use a narrower profile on the front tire too - a 265/35-19 - which, admittedly, would be to the car's benefit in terms of handling, but not without making the ride notably harsher or inviting dented wheels. Besides, my goal is purposeful change to achieve something specific. I'm glad to make compensatory changes that limit the effect of any alterations, but I don't want to start changing things JUST for convenience's sake. Besides, I'd be forgoing tons of terrific tire 40-19 front tire choices.

 

I'm sorry for being verbose, but I wanted to clearly explain my rationale, what I'm trying to achieve and why I have the misgivings I do.

 

Would I be likely to notice any negative effects by simply substituting a 27" diameter rear tire and worrying about nothing further, or is it worth taking measures to either lower the front in tandem, or seek-out springs with the SVTPP's 41.00 N/mm rates but ½" taller?

 

I realize people make far more dramatic changes to their cars' suspension setups and tire configurations everyday - without a great deal of notoriety about things gone wrong. Then again, people also generally don't tend to brag about things that haven't worked out as well as they planned. Am I worrying too much about nothing?

 

I'm far less concerned about appearance for appearance's sake - using the 19" FRPP look-alikes does more than enough for me in terms of keeping things tidy appearance-wise, and I'm far more likely to favor 285/35-19 than say a 285/30-20 on the rears to keep an extra bit of sidewall given the higher spring rates - and to try to keep as much of the balance the SVTPP managed to strike which I'd be bloody unlikely to ever replicate on my own - except by accident. But I've certainly not ruled-out anything that would deliver an optimal outcome.

 

In fact, I've even bought a set of the forged 18" SVT wheels so I can have a set of touring wheels and tires whose sole purpose is comfort over distances - as much to achieve optimal comfort than to free-up my decision making for whatever I wrap around the 19s and 20s.

 

I'd appreciate any experience-based insight from anybody who's undertaken a similar effort - particularly with respect to whether or not it's worthwhile pursuing wheel-specific rear springs.

 

Thanks in advance.