Andy13186

Thinking about getting 2 17x10.5 hypercoated bullitt rims and putting 315 eagle f1 gs-d3's on them on the back, then 17X9 front hypercoated bullitts with 275 kuhmo exsta xs's on the front.

or just kuhmo ecxtas xs on both front and back

Would the exsta xs have more grip on the front than a gs-d3 and therefore counter the increased grip by the larger rear tires, restoring oversteer instead of having understeer?

thoughts? I figure this setup would be awesome.

would be way more tire than i need i suppose as a mostly stock GT.. but i bet handling and overall driving performance would increase greatly over these 3 yr old nitto 555's.

Jazzer The Cat

I understand your thinking, but this is not the way to address understeer/oversteer issues

I like to see the same tire at all four corners for consistancy in grip. Luke of Tire Rack, just yesterday, mentioned an issue of which I had not thought and is with the ABS & Trac-Control systems. Assuming you have ABS, it "may" be thrown for a loop because the front tires would have more grip and less likely to lock up. In such a case, the ABS would kick in too soon and might cause some funny braking issues. I said "may", because on the SN95, I don't think it is possible to lock up the rears, unless maybe you were on ice or snow... lol. My recommendation is to address your suspension needs with suspension parts and not tires.

If you want your car to handle better, you can see much improvement via replacement of your 555's. They are a nice tire, but are middle of the road, as Summer performance is concerned. The Khumo Ecxtas XS will offer MUCH better grip and specifically speaking of it in a latteral sense here. I have run the GS-D3's and my current Michelin PS2's are a much better tire for braking and latteral grip. I have a REVIEW between them, if you are curious.

As for oversteer/understeer and handling questions, take a peek at the Official Suspension Guide and head over to the Suspension section for questions.

Jazzer

Andy13186

well i defiantly do want staggered wheels, and i dont see how i could get equal grip in front and back with the same tire but different sizes(much wider in the back). which is why i thought stickier in the front would help overcome this issue and possibly provide handling benefits.

The main thing i dont like about the nittos is their soft mushy feel in turns.

if i was sticking with 245's id just get the direzza star specs but, they dont offer those tires in the wide size, it seems like the only good performance tires in 315 and 275 are eagle f1 gs d3's or the exsta xs's.

I doubt i would ever brake hard enough with these , atleast in the dry, to ever require ABS.

I dont want to mess with the suspension much if possible. I daily drive the car and i dont want it too harsh or too low.

Do you have 18 inch rims on your car?

Jazzer The Cat

If the NT555's are "mushy" in the turns, I would check the tire pressure or ask what size the tire and width of wheel (all three tire numbers, please) They don't have a particularly stiff sidewall, but maybe you mean they slide or just don't grip well...?

Don't let anyone tell you that a car must ride harsh to improve the handling. While it is true, that to get real good handling Mustang, you will need to live with some NVH, but you can do a few things to not only help handling, but improve the ride. A good set of dampers will do both and a set of FLSFC's are another. You will "feel" the road a bit more, but not really in a harsh way.... just more connected to it. If you want to be "part" of the road.... then you have The VIXN (my car!)

yes, I run 18" wheels on my car in a 30 series tire. Keep in mind, that the higher performance tire you run in the hopes to improve cornering, the stiffer the sidewalls and more expensive as well. You may consider going with a 17" wheel and that Khumo Exsta tire. The slightly taller sidewall will help your ride quality, but the rubber compound/tread pattern will aid in your latteral grip.

Thoughts?

Jazzer

Andy13186

The nittos are 245 45 17's on stock bullitt rims. They just felt alot softer in the turns than my previous tires which were some cheap tires but had stiff sidewalls.

hard for me to decide , your 18's look good thuogh

Jazzer The Cat

A 17" wheel seems like a pretty good choice for you. If you want to address some understeer (the SN95 is prone to this), I would recommend looking into a heavier rear sway bar. It is a nice option to replacing rear springs, but is a bit of a short-cut, to be sure. The bar does not really add a harsher/stiffer ride, so much as lessen the body roll and help to keep the front end a bit more planted on the road.

If you want to run staggered wheels/tires, than issues of understeer become more evident. The wider the rear wheels become, relative to the fronts, the heavier a rear bar is needed to compensate. Again, springs are the correct answer, but a heavier rear bar will do wonders for moderate understeer issues and is exactly what I have done on The VIXN

Jazzer

Luke@tirerack

before you even think about sizes you need to consider differences in rolling resistance, sidewall deflection rates, water evacuation rates, etc. that different tires have ...

the two you mention are not very compatible

Ecsta XS = tons of dry grip, relatively weak sidewall rigidity and scary and unpredictable in the wet

GS-D3 = great wet traction, nice ride quality and steering response with less dry grip