Are STICKIER tires in the front a way to reduce...

[mareakin]

full title: Are STICKIER tires in the front a way to reduce under-steer?

I just replaced the front passenger tire (which was an H-Rated Altimax HP 195/60R15) with a V-rated tire Altimax HP tire of the same size.

It "feels" like there is less under-steer? Am I imagining it? I don't think so. When differences are subtle, I can never be 100% certain about it.

But, in general would you say that running stickier tires in the front is a way to reduce under-steer?

Final question: is it accurate to say that under-steer is ALWAYS about tires slipping? Sometimes weight distribution and suspension design can reduce or accentuate under-steer but bottomline: under-steer = tires slipping. IS this understanding accurate?

UPDATE: Car is 2007 Corolla CE with 15" X 7" wheels

 

[Astro14]

so many factors in understeer - weight distribution, tire size, suspension geometry. But really, forget tires - look at aftermarket roll bars (sway bars) for this car. Sway bar balance has a huge impact.

It would help to know make/model/year of your car to answer more precisely....

 

[rpn453]

Yes, probably not, yes, yes, and yes!

 

[mechanicx]

I would say yes stickier or more tire grip usually means less understeer, and your second question understeer is generally tire slip angle. The more front tire slip angle the more understeer and usually less grip. Although there is roll understeer particularly in the rear that is designed into the suspension links to cause the rear to toe in and more understeer.

 

[440Magnum]

More grip in the front does reduce understeer. If it were a rear-drive car, I would say you should be careful because it can turn to OVERsteer. But a front-drive will plow like a dump truck pretty much no matter what, so you're reasonably safe.

Under- or over-steer is always about tires slipping, but different things can cause the tires to slip, such as the ones you name. Weight distribution is the main reason FWDs understeer so dramatically, combined with the fact that the tires driving the car are already trying to slip which just compounds the problem. Sway bar stiffness and the relative stiffness of the front and rear bars is another big factor. Shocks less so, but also a factor.

 

[fsdork]

As others have said, there are a lot of factors involved in understeer.

With that said, I can say from personal experience that stickier tires have helped me correct understeer in the past. I went from the OEM Dunlop tires on my '08 Mitsubishi Lancer GTS to Toyo T1Rs, and understeer (particularly in the wet) improved dramatically.

 

[fsskier]

As Mechanicx says, your perceived understeer is likely the tire's slip angle. My first choice in reducing it would be to increase your tire pressures by a few pounds.... this often greatly sharpens your steering response.

Understeer is a very complex topic, a stiffer rear anti-roll bar would be the tuners choice-- being cautious to not do too much.
Wild oversteer is much more of risk to your health then understeer!!

 

[rpn453]

Originally Posted By: 440Magnum
. . . If it were a rear-drive car, I would say you should be careful because it can turn to OVERsteer. But a front-drive will plow like a dump truck pretty much no matter what, so you're reasonably safe . . . Weight distribution is the main reason FWDs understeer so dramatically, combined with the fact that the tires driving the car are already trying to slip which just compounds the problem . . .


You seem to live in a world where burnouts are fundamental to proper corner entry.

 

[Spazdog]

Wanna reduce understeer?

I put a pair of new Kumhos on the front of my Integra GS-R, left the age hardened Michelins on the back.

Pitched it into a corner and all the sudden I was Formula Drift Champion 'o the universe. Dorifto supahstah yo!

Okay, maybe not....but I could whip the back end of the car around at will.

It's not the sort of arrangement you want though.

You can probably find some better springs to start. I've driven RWD cars with overly soft front springs that had understeer problems. (and it didn't have enough power to even consider throttle oversteer)

 

[dparm]

Better driving technique is the ultimate cure for understeer.

 

[rpn453]

Originally Posted By: rpn453
You seem to live in a world where burnouts are fundamental to proper corner entry.


My sense of humor may have seemed kind of harsh there. If so, I apologize. I was a little irritated by the suggestion that my throttle-lift oversteer capable FWD car plows like a dump truck. All I'm saying is that the FWD = understeer and RWD = oversteer principle only applies when the wheels are spinning. During turn in, steady state cornering, trail braking, or even when accelerating out of a curve without wheelspin, chassis setup primarily determines how the car reacts, not drivetrain configuration. Therefore, you can easily get in oversteer trouble in certain FWD cars by having stickier front tires, as Spazdog detailed.

A modern Corolla is likely set up for heavy understeer though, and this isn't a big change in tire type, so there's probably little additional risk of oversteer involved as long as the back tires have good tread depth. Both tires have the same UTQG ratings, weight, and tread pattern. The difference might even just be due to the rubber being newer. Still, the conservative setup would be to run the new tire on the back.

 

[SteveSRT8]

FWD does not need wheelspin to understeer! Neither does RWD require wheelspin to oversteer.

Absolutely oversimplification. It's just not that clear of a distinction.

For example, my very good handling Neon R/T would oversteer dramatically with a firm brake application in hard corner. No lockup, just weight transfer off the rear tires.

 

[CapriRacer]

First, you're supposed to put new tires on the rear. That prevents losing traction on the rear first. Spin outs are not good for your health.

Also, the same rule says that the best tires ought to go on the rear - for pretty much the same reason. That means that the V rated tires should go on the rear.

Secondly, I'll bet what you are picking up is a difference in sidewall stiffnes and not grip - unless you are actually approaching the limits of adhesion - which I would not suggest be done on the street.

You should be aware that there are 3 kinds of understeer (oversteer). Initial turn in, steady state, and ultimate grip. The first is all about sidewall stiffness - how fast the tire reacts to steering input. This is commonly confusing to the averaghe guy.

The second is about slip angle - which is more about sidewall stifness - and differences in sidewall stiffness. Grip plays very little role here.

And the last - is about grip, but it only occurs at the moment the tire lets go - hard to judge without experience.

But vehicle handling is pretty complex. I suggest you get a copy of Fred Puhn's "How to make your car handle" - and read up, rather than get your info from a bunch of internet "experts" - and I'm including myself in that category.

 

[Craig in Canada]

Originally Posted By: dparm
Better driving technique is the ultimate cure for understeer.


Regardless of driver talent the chassis will still be tuned for certain characteristics. Formula 1 world champions complain about understeer too.

As someone already mentioned, more rear sway bar (does a Corolla even come with one at all) would be an excellent way to dial the car to a more neutral state. As others have also already mentioned - don't go too far.

You can also tune with tire pressure. Increasing tire pressure increases response but reduces ultimate grip. Depending on which kind of "understeer" you are complaining about - tune accordingly. If the front is slow to react but is otherwise OK - raise the front pressure. If you're plowing all the way through corners, raise the rear pressure and lower the front.

I've also found that on the same car even matched sets of 4 tires can result in different car balance depending on the tire. On T1Rs and PS2s my BMW is quite neutral (after increasing the rear bar a couple of mm). On Arctic Alpin snows it was neutral. On Dunlop M3s it understeered like a freighter no matter what I did and then transitioned suddenly to snap oversteer as I was playing with pressures. On my current Hakkapeliittas it understeers but much less than on the Dunlops. Maybe your replacement fronts simply work better with your suspension design to reduce understeer...

 

[dparm]

Well when I see guys at the track or autocrossing where they understeer for 50 feet past the apex, I would be inclined to say it's usually a lack of skill. I'm not perfect either, and my S4 is quite front heavy. I've been known to understeer at times:

(at Tire Rack in Indiana)


My old Integra was almost neutral, which was amazing. It had a very well-tuned suspension.

I would recommend against ultra-sticky tires up front, because it gives you a false sense of security. You'll be more prone to overdrive the rear and when that breaks loose you're toast.

 

[YZF_Eric]

What does the speed rating of the tire have to do with overall stickiness?

 

[440Magnum]

Originally Posted By: rpn453
Originally Posted By: rpn453
You seem to live in a world where burnouts are fundamental to proper corner entry.


My sense of humor may have seemed kind of harsh there. If so, I apologize. I was a little irritated by the suggestion that my throttle-lift oversteer capable FWD car plows like a dump truck. All I'm saying is that the FWD = understeer and RWD = oversteer principle only applies when the wheels are spinning. During turn in, steady state cornering, trail braking, or even when accelerating out of a curve without wheelspin, chassis setup primarily determines how the car reacts, not drivetrain configuration. Therefore, you can easily get in oversteer trouble in certain FWD cars by having stickier front tires, as Spazdog detailed.

A modern Corolla is likely set up for heavy understeer though, and this isn't a big change in tire type, so there's probably little additional risk of oversteer involved as long as the back tires have good tread depth. Both tires have the same UTQG ratings, weight, and tread pattern. The difference might even just be due to the rubber being newer. Still, the conservative setup would be to run the new tire on the back.


No worries, my skin isn't that thin and I did see the humor ;-)

And in my first post, I definitely let my personal dislike for FWD handling make my comments a bit more extreme than necessary. I like being able to have *some* direct control over the back end of the car, even if its only feathering the throttle to encourage or discourage more slip angle relative to the pavement, and I don't like my throttle application to have such a direct and profound effect on my steering inputs, either. But that's personal taste- there are guys out there (you included, maybe) who can do things with an FWD that I could never do with a RWD.)

So yes I agree, an FWD can be neutral or even have a touch of oversteer when rolling freely through a turn. But its not very *typical* of FWD vehicles at all, if nothing else because they tend to have an extreme forward weight bias. Add to that the fact that when the drive wheels are either applying engine braking or applying power, their slip angle is prone to increase even before traction is actually lost and you have a *fairly* good generalization that "FWD cars understeer." No, its not perfect. Yes, it applies to a Corolla.

 

[440Magnum]

Originally Posted By: YZF_Eric
What does the speed rating of the tire have to do with overall stickiness?


In a direct sense, nothing at all.

But in practical terms, no one makes an extremely high speed-rated tire that is NOT fairly sticky. However, in the middle range of speed ratings its not that hard to find a pair of tires where the one with the lower speed rating might be a bit stickier. But if you're comparing S rated to Z rated.... well, don't bother trying to find an S that's got more grip than the Z.

 

[Papa Bear]

Originally Posted By: mareakin
full title: Are STICKIER tires in the front a way to reduce under-steer?

I just replaced the front passenger tire (which was an H-Rated Altimax HP 195/60R15) with a V-rated tire Altimax HP tire of the same size.

It "feels" like there is less under-steer? Am I imagining it? I don't think so. When differences are subtle, I can never be 100% certain about it.

But, in general would you say that running stickier tires in the front is a way to reduce under-steer?

Final question: is it accurate to say that under-steer is ALWAYS about tires slipping? Sometimes weight distribution and suspension design can reduce or accentuate under-steer but bottomline: under-steer = tires slipping. IS this understanding accurate?

UPDATE: Car is 2007 Corolla CE with 15" X 7" wheels



You are talking about a 2007 Corolla here ??!! Do you race this thing ?
As usual, our BITOG enthusiasm has taken us from driving the streets of suburbia to 4 wheel drifts at Watkins Glen.
I guess my question (as a previous Corolla owner myself) is "What are you trying to address in your original post?"

I certainly wouldn't expect much if I took my Uplander to the skid-pad/slalom.

 

[440Magnum]

Originally Posted By: Papa Bear



You are talking about a 2007 Corolla here ??!! Do you race this thing ?
As usual, our BITOG enthusiasm has taken us from driving the streets of suburbia to 4 wheel drifts at Watkins Glen.


Why do people think understeer is only detectable at the limits of performance? Yes, the understeer/oversteer characteristics may CHANGE or become more pronounced at the limits of performance and in fact oversteer is generally only felt under extreme conditions, but generally you can feel understeer (if its present) during a 25 mph turn onto a neighborhood street.