Surely the answer is "it depends".... I don't fancy 205 rears on a turbo for example.. (also not on 8.5/9J rims). But you do appear to be acknowledging that wider & lower profile tyres will give you more, not less, grip.
laterial Yes, but with side effects.
That's why Porsche went (Staggered) wider rim and Tyre on the 951 (having previously has a square set up for almost 10 years) so that the balance with more power remained as understeer, the wider rears have a slower slip angle than the fronts due to their wider contact patch, so lateral loads (Cornering) the rear will not slip first but the front will.
But when any axle does slide it releases quicker and more sudden on low profile tyres than Higher progressive ones, which is harder to catch. Hence it's safer than a front tyre slides more progressively first before a rear does suddenly for
your average road user.
There is the factor that front & rear tyres also need to each cope with different functions (Front : grip when Turned and for braking) and the rear (traction & Braking all without no turning) Too wider a front tyre can be difficult to turn in crisp as there's too much scrub from the wider contact patch, as a contrast think how easy the longer patch narrow tyres turn, it's more difficult these days to feel because everything is power assisted...
The early model 951 had 7x16 205/55/16 and 8x16 225/50/16 the skinnier fronts when pushed hard will "tuck in" and head towards a positive camber situation and slide before the rears will, which is what Porsche want for Joe blogs.
For those who want to eradicate the excessive understeer, you could go bigger front but it's not the front that's the problem, and besides the 7" 205 front works and "turns in" very well, so you could change the rears to 7x16 and 205/55/16.
But this is frowned upon because some people think the rear needs to be wide because it's rear wheel drive and if they went narrower it would wheelspin, (which is not true) not to mention the "Look" wouldn't look right would it?
But I've built a lightweight powerful car unyet it wears 7x16 and 205/55/16 on all 4 corners and the handling & control in all 3 planes is the best I've experienced so far from any transaxle (924 / 944 / 968 / 928).
It's perfectly balanced @ 252kg each corner, and unyet has no wheelspin, braking or cornering grip issues, quite the reverse.
I've not fitted wide rims and tyres on purpose (Because it would be slower, not handle as well as it does & harder to drive) all based on my research and testing done over a 14 year span, on all 3 models and with wheels from 15" to 18" diameter on 8 transaxles (924 + 944+ 968) all tested for Road conditions (Not track)
I've also had all the track (Width) variants the early 944 (Short wishbone / low offset) and the later 944 (longer wishbone / higher offset) and also the Evo3 bodyshape (968) which I found was quicker with narrower wheels and tyres.
In 2012 I picked what I saw as the best chassis & Body of the bunch to throw 25K at, the narrow bodied 924 in S guise.
Not the wider track 944, because the narrower track widths feel better to me, the body has less drag the wheelbase to track ratio is longer for better stability, and it "turns in" quicker than the early model or the later model 944 & 968
When Porsche made the early 944's they somewhat disappointedly didn't change the suspension to move the wheel out to meet the wider arches instead they changed the wheel offset to Et23 so that the wheel was in line with the arch.
They did rectify this on the later Oval dash models when the offset went back to the ET50's but they made the wishbone longer (Wider) which changes the strut angle / motion ration and from all the models I've owned and modified I prefer the original Skinny track width / offsets and strut angle.
I spent 10 years Racing in a sport where you can and do constantly change the track widths, tyre pressures and chassis stiffness etc.. Once you have the template and understand correctly what's happening with balance and handling, and most importantly what can be done to make changes to win races, it's addictive and Fun to have an advantage against those that don't understand. Call it a very competitive edge!
Some 944 17" wheels/tyre sets are lighter than the corresponding 16's. (But then, why not use 15's?...)
I agree I would use 15's but the Wilwood 6 Piston calipers foul them, so I had to go 16 and then I went about lightening them to get close to the 15" weight.
I prefer a Formula 1 set up: Small Diameter wheel / Big sidewall tyre
With lots of compliance and movement in the tyre but stiffness in the chassis / suspension with less travel. I've found stiff suspension, reduced rideheight + Stiff Tyres (Low profile) is too much for the Road because it's less controllable, Tyres come off the floor, it's skitty and less compliant. which is why I was happy to see F1 also decided against 18" Wheels for the same issues I'd experienced and it like many car enthusiasts were only contemplating the change to improve the
"look".
As I've written before, we can and should appreciate the diversity of applications and configurations within the transaxle platform without trying to proclaim one "the best" or "the fastest".
Yes, but I cannot lie and agree on something that is clearly not the case.
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