KahnBB6

iTrader: (5)

As you say, wider tires (and rims) all around as compared to stock does help improve the handling and feel of any SC. Those 225mm tires in a square setup were never ideal other than for the stock floaty luxury/comfort feel.

And while it is normally not wise to mess too much with an already dialed in suspension or to use anything but a square tire setup on a FWD or AWD car, there is a precedent for this with a rear wheel drive car like the SC.

To improve stability and grip the rear tires being wider than stock help significantly. The reason to stay with a much narrower tire in the front, such as a 235 or 245 is to dial in some degree of understeer in addition to whatever the alignment settings will be. At least from a balance perspective this staggered setup ion 235 fronts has some more understeer but slightly faster turn-in than if you had 245's up front or 255's.

Once you start adding in an aftermarket coilover suspension, a more aggressive or MKIV style rear swaybar, an LSD and modified alignment settings... not to mention more horsepower... larger rear tires than fronts in a car like this make more sense to promote not only better traction but better control with a safety margin. It also depends on how that particular brand of tire communicates and behaves in different conditions.

Also, I'm not sure of the widest width tire that can be fitted up front without rubbing but it will not be close to the widest width rear tire that can be fitted to SC's or MKIV's.

I have read of a few Supra MKIV Turbo owners who road race using a square tire setup with custom alignment settings and possibly aftermarket adjustable control arms but they are the exception rather than the rule. Control of a powerful RWD vehicle on a perfectly square tire setup with a lot of power is different than with a staggered tire RWD.

Also, the ABS system works fine with any suspension and wheel/tire configuration. The only difference between SC's and Supra NA's and the Supra TT's in terms of ABS was that Supra TT's got 4-channel ABS plus a G-sensor whereas all SC's and all Supra NA's got a 3-channel ABS system and no G-sensor. From a handling and safety perspective either version of the ABS system is very effective. The Supra TT's ABS is just slightly more "track" tuned.

In general there are numerous RWD cars both front, mid and rear engine that use staggered tire setups from the factory. Even Honda's S2000 uses slightly staggered tires.

However any FWD or AWD vehicle regardless of how much performance tuning and power it has or lack thereof should not be using anything but a "square" tire setup. That is unless the FWD vehicle is specially set up for drag racing but that's not considered a "street" oriented setup anyway.

But with a car like an SC it makes total sense to stagger the tires for performance handling benefit. It's just not required depending on the intended use and suspension setup. 245's all around in a square setup can be very good unless you want to maximize the potential of the suspension.... and handle far more power than the stock NA engines provide.

t2d2

iTrader: (8)

Sorry if I wasn't clear. I only ran 225s up front. I had 245s in back.

As for the ABS issue, I was referring to calibration, not functionality. Here's a random search result from among many similar:

Q: Will bigger tires affect abs?

A: If your car or truck has antilock brakes (ABS), vehicle manufacturers advise buying new tires that are the same size as those installed at the factory. The reason: the diameter of the tires affects how the wheel speed sensors read, which affects the operation of the ABS and traction control systems.

Dokuji

If your current tires are unsafe, then tires first absolutely. Otherwise, do coils first, then wheels and tires together when you figure out what sizing you want to run.

Safety first. Just depends on your budget for the rest of it.

KahnBB6

iTrader: (5)

Ah, ok. I could have sworn you said you had run a 245/245 square setup. 225/245 staggered is very mild but just fine as well. Wheel width also factors in depending on how stretched the sidewalls are. I feel that's a chief complaint of the Supra TT's stock 255 rear tire width on the stock 9.5" wide rim.

As you've read there probably is an affect on ABS operation if your overall rolling diameters veer very wildly from stock but in practice with the 235/45-17 front and 275/40-17 rear setup and Supra TT brake calipers front and rear I have not had issues when the SC's factory ABS has been engaged in emergency scenarios.

My VSS speed signal from the transmission is intercepted by a Yellr Yellowbox V5 which is calibrated to compensate for the slight changes in rolling diameter and rear differential gear ratio from stock. The ABS sensors at the front wheels will have their own pulses which are not intercepted and compensated for by any aftermarket device but I have never heard of this being necessary.

Some have argued that with a significant enough brake rotor and caliper upgrade to an SC the ABS system is not needed or it undesirable due to unwanted weight. I disagree. Even with my setup I have found it to work perfectly and provide great safety benefits even with the slight rolling diameter differences from stock tires.

KahnBB6

iTrader: (5)

^^ I agree with Dokuji. Always address any safety concerns first. If at the moment your tires are worn out or beyond their expiration date (yes, even tires do have expiration dates believe it or not) then those should be the first priority.