Sleeper_08

The other alternative is to go with 285/40/18 on 9.5 rims on all 4 corners. The 285s are the same 27 inch dameter as stock and fit on the non lowered car with no rubbing. After putting in the Steeda Competition springs it rubs a little on full lock in the parking garage but nothing to worry about. The rims have to have a 45 mm offset for it to work.

Jazzer The Cat

Staggered wheelsarenot to blame, but rather the driver.

There is something to be said for same sizeon all four corners. I have found that rotation would have only helped once andwith my last set. I had heavy neg. camber on fronts and both inside/outside edges were completely shot long before the rears. Can't understand why

Guess I should do more doughnuts [8D]

Jazzer

Norm Peterson

Mikes - as far as coping with staggered sizes is concerned. . .

For anything up to some pretty hard street driving, you"ll adapt to the car before you realize on your own that it should be giving better behavior. Unless/until you"re actually feeling the slip angles at the two ends build as you corner or the front actually start to push without you adding throttle, any discussion of increased understeer is academic because there simply isn"t enough going on for differences in understeer/oversteer balance to matter. The tires are still behaving linearly or almost so.

Yes, in theory there's more understeer - ina steady-state turn taken somewhere up above about 0.5 lateral g, and yes that's usually a theoretical disadvantage. Think long, constant radius 270° Interstate exit ramps where you just have to be patient about doing anything but sit there and hold constant steering and speed. But it"s not all bad news to have a little more understeer if the reason for thatis that the rear tires have more grip (assuming that the fronts have enough if the rears were that size as well). When the rear tires have a little more grip, they have more of itleft for early throttle on corner exit if you"re smooth enough about using it and are driving hard enough to actually need it. Back to street driving, I"d guess it"d be a wash most of the time as far as total time from corner entry to 100 yards into the next straight goes.

It is possible to re-balance the car via shock tuning (if/when youget adjustables) for corner entry/exit and springs/bars and possibly tire pressure tuning for the steady-state stuff (mid-corner and those 270° loops). Mostly, you"d stiffen the rear shocks and either the rear springs or the rear bar or possibly all three. What you"re trying to do here is drag more of the cornering work back onto the rear tires since there is more grip back there to work with.

As I understand it, Ford had originally wanted to maintain 255/45"s all around on the GT500 but ended up having to go larger at the rear. In a lower powered car there is that much less reason to choose staggered tire sizes for any sort of driving (I"m assuming that your automatic still shifts smoothly both up and down and that you do not need to provide a little extra cushion against any harsh shifts tending to unsettle the car at a bad time).


Norm

Philostang

Ok, the gauntlet is thrown! I'm running 255/45 on all corners, and I'll take you up on that challenge Stoenr - it would be fun to head out to a course with some Chicago-based Forum members.

This is a bit off topic, but send me a PM and let me know what courses you're hitting this summer.
Best,
-j

Stoenr

PM sent.

F1Fan

Hi Mikes_BLK_GT,

The answer is as usual "it depends." When you say "handling" are you asking if the car's handling balance will be changed the answer is yes, without a doubt the handling balance will change. This is due to theimbalance in available grip witha staggered wheel and tire setup.An S197 Mustang with narrower front tires than at the rear (all things remainingequal) will have less potential total grip available soin a steady state cornering situation the front-end will loose grip before the rear-end will loose grip.But there's the rub, cars are almost never working steady state andeven when they are it's for fairly short periods of time. But anyway on a front heavyrear drive car like the S197 Mustang going with astaggered wheel and tire setup is not ideal as there is more weight on the front tires than at the rear and this compensates for the extra work the rear tires need to do what with providing forward thrust and all. So for S197 Mustangs same size or at least tires with the same potential grip all around is a faster setup for cornering AND braking.

That said the difference is not huge but racing is a game of inches and tenths and hundredths in a very controlled environment. On the street you cannot use enough of the potential of modern ultra-high performance tires even on UHP all-season tires to be seriously negatively impacted. If the differences in tire widthswere greater and the front tires were less than say a 235 wide tire I would complain more but I don't think you will really notice unless you go to the track or can run freely in your local mountains and canyons where the shortcomings of using a narrower front tire will make themselves felt unless you make changes to help balance the tire gripdifferences out.

In any case depending on what suspension is under your car you can compensate somewhat for the lower front grip of the staggered wheel and tire setup by going to alargerfront bar first (if you don't already have larger bars all around) and then a larger rear bar keeping the front bar rate cranked up. The trick is to find that magical combination of front camber, front roll resistance, tire pressure and damping to balance theadditionalgrip of the larger rear tires. Doing this can pay dividends in steering feel and responsiveness on an S197GT that you cannot get any other way except with the wide wheel and narrowertire sizedcloser to the narrow end of the usable range of widths for a given wheel width. Somevery highly esteemed sports coupes and sedansof modest power, withwell balanced static weight numbers,front engine and rear drivechassis layouts go with staggered wheels and tires for this reason and achieve what can only be described as sublime handling.Our S197 chassis is basically a copy of said sports coupe and sedans of course we are some what limited by the live axle out back but this is not really a limitation so much as some would have you think except over bumpy road surfaces. But staggeredwheels and tiresis not necessarily the fastest way around a race track.

I can tell you that the staggered wheel and tire setup can achieve very high levels of grip and you can get the front grip to work in harmony with the rear tires. I'm not sure just how well my car relates to your car in terms of chassis work because my car is somewhatmodified. But even a car on conventional struts and springs with aPanhard barcan be set up to work reasonably well at the limit on a staggered wheel and tire setup with some suspension work and tuning time.

I had a set of forged Roush 18x10 wheels all around rolling onBFG g/force T/A KD tires which are some of the stickiest true street tires (not wear factor ofzero or 'R' compound)on the market. The tires were275/40x18 all around and the car was unbelievable in terms offront grip and braking power. I loved the sheer grip of the larger tires in front and the limits with these tires was very high. But I just really don't likechrome wheels so I sold them to a buddy of mine who saw them one day at a car gathering and was Jonesing for them.

I had acouple of sets of Saleen PJEdition wheels (19x9's and 19x10's)sitting out in the garage waiting for the tires I wanted tocome off of national back order. Still back-ordered so I bought a set of Goodyear Eagle F1 A/S tires in 275/40x19and had them mounted and balanced. They fit in front but just barely (could have used anextra5mm offset)and while the front grip was quite good the steering feel was slow due to the 275 wide tire on a narrower 9"wheel. So I ordered a pair of 245/45x19 Eagle F1 A/S tires and had them mounted and balanced and put them on the car. WOW! What a difference in steering feel and responsiveness going to the narrower tire made. Of course the ride suffered slightly as predicted but the car really woke upsteering wise. But now the car was not as well balanced as I had it working withsame sized tires all around. So I upped the rear balance by softening the front bar all the way which brought the car back balance wise but the front grip was not as good. So Iwent back to the full stiff front bar setting and installedthe stiffer GT500 rear bar that came with the Saleen Watt's link and the front grip and handling balance is now closer to the previous handling balance and grip levels.

But the difference in steering feel and response even when compared with the10" wide Roush front wheelsand sticky BFG g-force T/A KD's is excellent which makes the car a lot more fun to drive quickly in the twisty bits. I'vetest the setupon Mulholland for over 100 milesyesterday and I'm pretty happy withthe way the car is working dynamically.The front grip limits are stillnot as high as with the BFG g/force T/A KD tires but overall the car is a better more lively drive on the street. At the track I think the car will be a bit slower than before.

HTH!

F1Fan

Hi Jazzer,

You needed an alignment and/or more tirepressure in front.

HTH!

Jazzer The Cat

Nope, just need to have less neg. camber and be easier in the twisties (like that is gonna happen [8D]) The inside wears b/c of very aggressive camber I had and the outside was worn due to HWY 1 twisties.

I will get my car back in the next day or so with the full SLA upgrade from Griggs Racing so I will no longer have either issue in which to deal [sm=Awwww.gif]. I should have very even wear along the surface of the 295/30 R888'srunning up front.

VERY EXCITED to get The VIXN back on the road with new Summer tires/wheels this week. Jonsin' in a MAJOR way

Jazzer

Mikes_BLK_GT

Thanks for all the info this is great and will certainly help. Currently(and this may change 50 times before I actually act) I'm looking at the Steeda Pentar's(black) 18x9.5 with 275/40's all around. If I can get the right size I want to stick with the BFG's and will need the all-season version( I live in the Pacific NW). Right now my suspension is mostly stock at this point, I have the FRPP handling pack but want to change to the d-specs. I also have LCA's, G-trac braceand adj P/H bar & brace which will be installed hopefully by the end of July, and am considering the GT-500 front CA's since they are about half the price of all the others I have looked at and do 99% of my driving on the street.

Norm Peterson

Just how aggressive is that camber? And if it really is that much, why would there be rapid outside shoulder wear?

I"m thinking more along the lines of toe (-out)+ bumpsteer effects + hard braking is what"s killing the insides. And low pressure with relatively narrow wheels for the tire size is hurting the outers by letting you roll over onto them.

Even with the SLA upgrade, you"ll still want to tinker with the tire pressures to put the handling where you want it. Make that because of that SLA upgrade that you"ll have to. Look for little triangles molded into the shoulders of your tires - they"ll bedown in the tread voids - and set your pressures so the scuffing under hard cornering goes into, but not past,them. If it seems to take unreasonable inflation pressures to make this happen, the wheels are probably just too narrow for the combination of that particular tire model and size and your driving.


Norm