I want to undertake the small little and safe things to improve my ride: Will using standard touring all-season tires in the rear while using “high-performance all-season” tires in the front reduce under-steer?
Car: 2007 Corolla on 195/60/15 General Altimax HP tires.
What do you use this car for, and what is the climate like where you live? When do you experience this understeer? Generally speaking, the idea you have is not a good one. The safest thing you can do with tires is to make sure you have matched tires at all four corners. Ideally, you should have all the same brand, and keep them rotated so they wear evenly. Mixing tire types is not generally a good idea.
This car is for street driving… I often drive on roads that have been often-driven on–by other cars: the roads of NYC (Manhattan, Queens, Brooklyn, Bronx) I think can be categorized as “poor” and not-smooth.
If you are reaching the point where you can tell the difference in grip at the front, then you are in danger of losing the grip at the rear - and you do not want to lose grip in the rear. You would be pointed the wring way to steer.
A better idea would be to look at suspension kits with different sway bars and shocks, and a COMPLETE set of high performance tires.
There is no safe way to check adjustments you make to the tires or suspension unless you have a race track nearby, or a very large empty parking lot. After making changes you’d have to push the car beyond the traction limits and see how it handles and responds.
You can change the understeer/oversteer characteristics of your car with different tire pressures in the front and rear. Lower in the front, and higher in the rear will increase the tendency to oversteer. This means the rear end will break away quicker than before. Is this safe, likely not. Which is why you need to test how it drives on a track or other safe area.
Please follow CapriRacer’s (and everyone else’s) advice - you are proposing something that’ll make your car unstable. First step: Go to tirerack.com and see what they have for a set of high performance tire for your car. That alone will make a difference. You then could check if they have performance shocks/struts/springs, and you could also go to a new set of 16" (not 17", typo on my part) wheels and lower-profile tire. You’ll lose some ride comfort with steps 2 and 3, but gain cornering. Note: ALL fwd cars will understeer to some extent, a consequence of the weight distribution. If you want better, get a better car, Miata for example.
I would not recommend going to a lower-profile tire since the OP states that he lives and drives in NYC, where the streets are pockmarked with a large number of very large and deep potholes.
Lower-profile tires will not be able to absorb the impact of hitting those potholes as well as the current 60-series tires, and may actually wind up leading to damage to the wheel rims. “50-series” (or, God-forbid, “40-series”) tires themselves will actually be prone to damage to the tire sidewall from driving in that type of environment, and then the shock of the impact is transmitted to the wheel rims.
Likewise, high-performance struts and springs may not be well-suited to use on those badly-maintained urban road surfaces.
And then, there is the inevitable question for the OP:
If you are experiencing understeer problems while driving on NYC streets, have you considered the possibility that you are simply driving too fast for the environment?
Reducing understeer could lead to oversteer. Oversteer is bad, unless you’re a professional racing driver. Are you?
I agree with all your points. It’s up to the OP what compromises and expenses he’s willing to endure…
p.s. - my mistake on wheel size, meant to say 16", since corrected.
Tirerack says 205/55X16 would be a fit if going to 16". I don’t think the ride and durability would be too compromised with those tires.
The biggest changes you can make to your car to reduce understeer is to increase the width of your tires, in conjunction to increasing the negative camber amount. For a front wheel drive car, you need to have some toe-out so that the wheels will decrease that toe when under acceleration. If you have toe-in, the toe-in will increase even more, which is not good at all.
If you are doing extreme driving in NYC on the parkways, please stop.
If you are actually going to the new raceway, add some negative camber, and a tiny bit of toe in to the rear. DON’T LOWER THE CAR unless you are having an actual professional shop make adjustments to the location of the control arms.
Trust me on this.
If you slam a Corolla to the ground, you are going to ruin the handling while giving her all she’s got through corners. At the most, the lower control arm needs to be level with the ground while she’s at her most extreme leans through corners. While cornering, if the lower ball joint is higher than the connection point of the control arm at the frame, you are going to have an extremely unstable rear end. Bump steer will be your worst nightmare.
BC.
If you want a little more oversteer, you might want a rear drive car but unfortunately none are available in the Corolla size category unless you can find something used and it would be quite old. I like a little oversteer to kick in too when I want it.
It’s interesting that my 09 Chev Cobalt has the battery located in the trunk to move approx 50 lbs. from the front to the rear of the car. That is approx. 1.8% off the front and 1.8% added to the rear, a total change of 3.6%. The battery location is as far back in the car as is possible and is on the passenger side.
IMHO the best way to reduce understeer without having a significant impact on ride or having other adverse effects (such as the increased hydroplaning you might get with wider tires or the instability you might get by mismatching the tires on the ends of the car) is to install an upgraded rear antisway bar (or both front and rear). Check the Hotchkiss website and see if they offer one for your vehicle.
In addition to reducing understeer, a better sway bar will also reduce leaning in turns. Both things, understeer and leaning, are related.
Good idea, TSM, turns out TRD makes a sway bar set for this Corolla, about $160 on the web…