195/55 slowed my car down

[scape]

8(

feels like someone is sitting in the passenger seat now, if y'all know what I mean...
I looked it up, and these new tires do not weight very much (17lbs from tirerack), however I do think that the tires that get stocked for new yaris' aren't necessarily the same exact as what tire resellers get. let me explain...

I looked on bridgestone's site and the tire weight of re92's for 185/60/15 is 17lbs for yaris, and 205/55/15 (celica) is 15 lbs (http://www.bridgestonetire.com/tires...x?Product_ID=8 ) ...tirerack(which I contemplated being incorrect) went with generic sizes and not car specific, but the same tires pull up 18lbs and 19 lbs (http://www.tirerack.com/tires/Spec.j...e1=yes&place=2)...

so I emailed bridgestone to figure this out: "the tire weights for re92's seems inaccurate. 205/55/15 is 15 lbs, while 195/55/15 is 19...also these are all whole numbers, if the actual weight was expressed as say 15.9, that would be beneficial as that is much closer to 16 lbs worth of tire and worth noting."

reply: "The Potenza RE92 is an original equipment tire. Therefore, the specs are set according to the vehicle and vehicle manufacturer specs. So, you could possibly have the same size tire with very different or slightly different specs and/or weights."

so it becomes apparent that the light tire is sold as oem, but it may be impossible to actually get that same tire again...

but I guess this misinformation isn't new, b/c general's site claims my tires are 16lbs a pop (http://www.generaltire.com/tires/T1/...m-UHP)...which somehow i doubt from the feeling of things

-just thought I'd vent this one out :D

[Sabretooth]

Even though the weight is less, you increased the amount of tread that is on the ground. Which in turn increased your contact with the road, if your running the same rim, and same weight tire, your adding more friction with the road.

This means your car is using more energy to move the tires since there is a larger surface area to move. On the flipside, you increased your surface area to the ground, so your handling should be a bit better, depending on the tire.

[scape]

handling's great, but i had no idea that that amount of friction could do this; drastically different :(
i wouldn't want to know what a 205 feels like, haha

[Sabretooth]

205's arent bad, it all depends on what kind of weight difference between OEM tires/rims, compared to the new stuff. If you end up with a lighter tire, then a lighter rim. Overall your performance should be better. Most people focus too much on rim weight when it is just as easy to splurge on a good tire, then only to realize it weighs more than the tires you had before, which can throw away any and all gains you made with the weight reduction of the rim.

It all plays out, I figured MY Yaris will never be able to blow the doors off a car in a straight line, so the sacrifice of the larger tire for a much better handling feel.

[Thirty-Nine]

I've run 185s, 195s, and 205s on my Yaris and was never able to tell any difference, personally. I've got 195/55/15 tires on now.

[kimona]

I run 205/50/16's, and I notice no significant difference whatsoever over stock 15's... except of course the car handles remarkably better now.

Check the diameter of stock vs. your replacement size tyre:

185/60/15 = 23.7
195/55/15 = 23.4

[scape]

could something else be wrong? it feels much more sluggish, to the point that I've stalled in first twice in 2 days, which almost never happened...

[Tamago]

what are your tire pressures?

[scape]

i'll have to go check them, they look well inflated-- and i did just get them put on two days ago so I imagine the tire installers did things properly

[Tamago]

Originally Posted by scape

i'll have to go check them, they look well inflated-- and i did just get them put on two days ago so I imagine the tire installers did things properly

fyi 32 psi is not enough

[Thirty-Nine]

Originally Posted by Tamago

fyi 32 psi is not enough

Really? I'm running 32 PSI in my 195/55/15 ...

[scape]

i'm almost certain these were setup at 32psi, but i'll double check... what would you recommend?

[Tamago]

Originally Posted by scape

i'm almost certain these were setup at 32psi, but i'll double check... what would you recommend?

depending on how much of your rear interior is, i'd recommend 36 up front and 32 in the rear.

[scape]

would higher front wheel pressure increase understeer?

[bdc87]

I had a feeling similar to yours when I had 195's. Got better grip but felt as more weight had been added cause of the friction. I'm now going to a 175 on a 14" rim. The tires weigh a little over 15lbs, should be interesting.

[Tamago]

Originally Posted by scape

would higher front wheel pressure increase understeer?

it depends. there's a fine line of grip that's very pressure sensitive. if you want the car to rotate better, definitely run the same pressure all around. remember your car is 60/40 weight split so adjusting tire pressures keeping this split in mind will help you change the overall handling of the car.

[Loren]

Tire pressures are a funny thing and very dependent on the car and tire.

Raising tire pressure can increase the effective "spring rate" of the tire, which is a part of your overall spring rate. Stiffer in the front = more understeer... in theory. The effect is much less on a performance tire with a really stiff sidewall, though. Those tires are stiff no matter what you do. The pleasant side-effect of stiffer tires or more pressure in the front tires is greater steering sharpness.

Raising the tire pressure can cause the tread of the tire to "crown", reducing the size of the contact patch. Again, less contact patch in the front = more understeer... in theory. But, again, a performance tire is likely to have so much radial reinforcement of the tread area that it will stay pretty flat no matter what.

On a FWD car or a heavy car, a more important thing to look at is how much pressure is required to keep the tires from rolling over onto the sidewall. This will over-rule the two items above in most cases.

Ultimately, you want to optimize the contact patch of the tire so that the entire surface of the tread is being used and yielding equal temps across the tire tread. The only way to tune that is with a pyrometer and skidpad testing. But, even then, unless you're willing to make some drastic changes to your suspension, you'll never reach that ideal.

Best thing most people can do is just air the front tires up until they don't roll over past the edge of the tread (there's usually a set of little arrows that mark the max rollover point) in hard cornering. That's going to vary greatly according to what tires and wheels you have, what alignment you have, and how hard you tend to corner.

[HTM Yaris]

I have 195/55/15 . For everyday stuff its 32 psi all the way around . For the Dragon its 34 psi all the way around . Not only do I rotate ,but I also "flip" tires when applicable . I also still have the original Goodyears that came with the car when I bought the car in 06 . I use the original tires from October to March b/c I do alot of offroad ( dirt driving ) . When I bought my second Yaris ( 09 ) I made the dealer switch the Bridgestones for the Goodyears . I think GY are better than the BS for year round everyday driving .