RR Rating for Falken Ziex ZE-912's?

[SpeedKnight]

So, the tires on my GTi are beyond shot. Because my personal driving style is very sprited, I want tires that offer great dry handling while offering pretty decent wet handling and relatively long treadlife. I'm not terribly worried about traction on snow and ice because I live in northeast NC and work in southeast VA where snow and ice are not usually a problem (and if the family travels anywhere that .

Anyway, I've researched UHPAS tires using online reviews from retailers and auto forums alike. As it turns out, the Falken Ziex ZE-912 garnered high marks from internet forums, and topped CR's list of the best UHPAS tires. Given these facts, I've decided to go with a set of these.

The overall question here is what the RRC for these tires is.
If I press these new tires to 40PSI (likely 4PSI shy of max), will I see any decrease in the mileage numbers I'm turning with the worn out tires?

[theholycow]

When it comes to choosing a tire model, rolling resistance is not a science, it's a black art. You have to make a deal with the devil to get real RR numbers. Failing that, it's a guessing game at best...and usually not worth worry about while purchasing tires.

I think you mentioned it in another thread, but how much pressure are you running now?

[thisisntjared]

careful. they get very loud, but since they are so cheap, can you really complain?

Originally Posted by SpeedKnight

If I press these new tires to 40PSI (likely 4PSI shy of max), will I see any decrease in the mileage numbers I'm turning with the worn out tires?

very likely but that depends on what you are currently running. usually worn out tires are the best for mpg.

[thisisntjared]

Originally Posted by SpeedKnight

If I press these new tires to 40PSI (likely 4PSI shy of max), will I see any decrease in the mileage numbers I'm turning with the worn out tires?

very likely but that depends on what you are currently running. usually worn out tires are the best for mpg.

[SpeedKnight]

Right now, with the worn out tires, I'm running 35psi. I've got it this low to give me some cushion from the swiss cheese like roads outside the Norfolk Naval Station. I may be out in left field on this, but I think actually having tread on my tires will give me some cushion, so I will run about 40psi on the new tires.

[theholycow]

I wouldn't count on a smoother ride from the new tires. More tread won't help. If they're made for good dry handling, they have stiff sidewalls.

[SpeedKnight]

Looks like I'm up a creek then.

Turns out, the OEM pressure recommendation is 38psi. Also, my front wheels have excessive toe in (I finally took a really good look at the tires... the inside edges are WAAAAY worse than the rest of the treads.
I'd be insane to not have an alignment done when I get the new tires.

Here's a question for you folks... would running a higher pressure no shift the contact patch more toward the middle of the tires, giving me a little more traction until I can get new tires?

[theholycow]

Your car has a label recommending 38psi? Is that for the same size tires you're running?

If the inside of the tires are worn, you have toe out.

If 38psi is the recommended pressure, 44psi or 51psi wouldn't have any effect on the location of your treadwear. My truck recommends 35psi; I run 80psi, and barely have any center wear at the end of my tires' wear, with no alignment problems. My car recommends 30 or 35 (I don't remember) and I run 51; I'm getting visible but not terrible center wear.

[thisisntjared]

Originally Posted by SpeedKnight

Here's a question for you folks... would running a higher pressure no shift the contact patch more toward the middle of the tires, giving me a little more traction until I can get new tires?

if you have no treads on the inside and your talking about being in the rain then absolutely! also fixing the alignment could net better mpg depending on how off it is.

Originally Posted by theholycow

If 38psi is the recommended pressure, 44psi or 51psi wouldn't have any effect on the location of your treadwear. My truck recommends 35psi; I run 80psi, and barely have any center wear at the end of my tires' wear, with no alignment problems. My car recommends 30 or 35 (I don't remember) and I run 51; I'm getting visible but not terrible center wear.

all tires are different and different tires respond to proper pressure differently

also where the tire wears also depends on the camber and caster not just whether it is toe in or out.

[SpeedKnight]

Actually, the OEM recommendation for tire pressure is for 205/50-15 tires. The previous owner put 205/55-15's on it. She apparently either had the speedo recalibrated or the extra 20.5mm (~.8") of tire height is negligible, because the speedo jives with my Garmin nuvi 260W, my wife's Garmin 255W, and the "Your speed is" radar unit on base. I'm contemplating 225/50-15's for the extra contact patch to improve handling a little more.

As for the alignment issue... ok, I'll admit it. Suspension and tire positioning have always been Greek to me. So I just looked up a quicky lesson on toe, caster, and camber. Where I haven't got the skill or tools to check for certain, but I'm willing to go out on a limb and say the toe is straight on (based on this graphic), my caster seems fine, and my camber is excessively negative (based on this.

I'm hoping that correcting the camber issue will mitigate any FE loss that full treads might give me. I'm certain that correcting the camber and having good treads WILL increase my wet and dry traction. This last part is a definate plus... I love me some high g turns. *grin*