froggy47

I am surprised how fast the rears are burning off on my c5z street tires vs. fronts, but I think I know why & it's not burnouts, I never do them with my street tires & very small when launching on a6/710's.

The rears are over 55% gone & fronts are maybe 15-20% gone.

They are Sumi HTRZ III 300 wear tires.

One track day on them, no autox.

Most of you guys know my alignment is very agressive autox/track alignment.

BTW the wear is very even across the tread front & rear.

What I think wears them is low speed street driving where a first gear turn is made from a stop. I do drive off "briskly" and I think the diff engages a little & there is a small amount of wheel spin on the outside wheel, not enough to engage tc but enough to "scrub" the tire on each corner.

Multiply this by about 5000 street miles since I put them on, mostly secondary roads.

Not really concerned or anything, but I am curious to analyze this as I had always figured that fronts wear out before rears even on RWD cars.

Any other analysis?

davidfarmer

check your toe also...excessive toe creates a lot of wear on the street.

crease-guard

Check you other toe as well...the one attached to the right foot. Excessive "heavy toe" will also cause the rear tires to wear fast

Jay

SoDiezl350

How do you like the HTR ZIIIs? I've read they are quite good dual purpose tire but a TW of 300 seems crazy for a tire in that class.

c4cruiser

One thing to consider about tread wear ratings is that they only apply to tires made by that manufacturer and can't be compared to other brands. So a 300 treadwear rating for the HTR ZIII is not the same as a 300 rating for a Goodyear tire or a Firestone tire or any other brand.

If you look at the survey for this tire on the Tire Rack website, it placed 15th among comparable tires.

They may be reasonably priced, but there a number of tires that would be far better for combining street use and autocross/track days

sebdavid

The inside wheel would be slipping, not the outside one.

froggy47

I was wondering about that, but either way it seems to "scrub" the rears when I drive off of a corner. Thanks.

froggy47

Tow in @ about 1/4 inch, is that enough to do it?

froggy47

As I said, I'm not a burn out guy, maybe slip the tires a little bit once or twice a week.

froggy47

For the money I like them a lot, I even tracked them once on the Fontana Roval up to about 135 on the banks & they were decent, not great, but decent.

Obviously there are better street/track tires, take your pick & pick your price. $$$

I bought these for just knocking around town, not for any "events". For how I use them and for the price they rock. I did not buy them for hpde, just happened to be what I had available at the time I did a spur of the moment DE with a buddy.

They make a ton of sizes too.

froggy47

A better way to compare tire compounds, if you have a concern/need is with durometer readings on fresh stock.

BTW I bought these for street use only. I think I mentioned that about 5 times in the original post.

froggy47

Thanks guys for all the good posts, I'm leaning towards a combination of:

1) Rear toe setting, which I don't bother to set back to zero after events. If I decide to run MORE rear toe I guess I will have to slide under & reset it at the end of the event (pretty easy).

2) Softish compound

3) Driving "style"

Probably in that order of importance, like I said no biggie, just my curiosity as to why it's happening. I will probably get 8-9k miles on the rears & maybe 20k on the fronts, so pretty good value IMO.

I have many sets of rims, so I sort of pick the rim/tire combination that I mount based on the event (or non event) that's coming up next.


YMMV

FastEddy

1/4 toe sounds like a lot on the street. The high performance street recomendation I was given for my c-4 suspension was 1/8 total, and I think when I first had the alignment done, the guy did 1/8 on each side, which gave me 1/4 total. I ended up going back to zero after having u-joint problems...which I dont think were related. Haven't had a chance to revisit the settings yet. I sure would think someone on here would have better advice for you, as well......

Also, just because the rear tires don't seem to be spinning, doesn't mean they are not fighting for traction, and slipping juuuuusssst enough to increase wear.....

The only car I EVER had that I wore the fronts out as fast as the rears was an old Euro spec BMW 635, with an Alpina suspension. It had decent power and incredible handling, but I was afraid of fragging the rear diff or the two piece driveshaft, so I was extra careful at being smooth both on and off the throttle, and spent most of my time in the car in the turns. The ZR's wore out in front and rear at the same rate. Every other car I've owned has a seen around a two rears to one front ratio, because 50% of my body weight is in my right foot.