kbreese

I'm kinda sick of the lack of traction with the stock GY's in my C5 Z06, where first and even 2nd gear is useless. So I am looking into getting a DR, particularly the Nitto 555R's. Only problem is the treadwear obviously isn't that great (100 treadwear rating) They are usually good for 10k-15k miles. So I'd like to get the NT555's for the front which have a 300 treadwear rating, which still look similar enough to the rears but won't have to be replaced as often.

My question is will the different compounds between front and back be hazardous? I don't do any autoxing or road racing, just the occasional spirited street driving, but I figured the crowd here would know best.

NT555 front 275/40/17:
http://www.discounttiredirect.com/di...70&rd=17&ar=40

NT555R rear 305/35/18:
http://www.discounttiredirect.com/di...31&rd=18&ar=35

Thanks,
Kevin

Last C5

It's probably not a great idea, if you want to continue with any "spirited street driving". That combination will drastically increase the C5's inherent understeer and even if you just end up kissing a curb, you're not going to be happy with yourself.

kbreese

Hmm, maybe I'd better get the 555RII's for the front than...

az55

I ran the 555Rll's with great success. The wear is even surprisingly good on the street. The only real difference in the DR is that the sidewall is much more flexible. If you are NOT doing a lot of twisties, the DR should be fine. I even ran them on the Phoenix road course one week end because they sent the wrong tire and I didn't have time to wait for the right one! I still took top time in my class that day.
Cheers,
CV

kbreese

Good info, thanks!

Bertram65

If you go to Nitto's web site and the tire size selector, http://www.nittotire.com/#index%2Esize staggered fitment
enter 275/35/18 front and 305/35/18 rear, Nitto reconmends NT555 front with NT555rs on the rear. So it is probably ok to run the two different tires.
I am thinking about running 305/35/18s NT555RIIs on the rear, I am just concerned they won't drive well on the street.

Last C5

That may be because they don't make a 275/35/18 in the RII.

Bertram65

True the NT555r is not made in a 275/35/18, but if you put in a size that is not available in the NT555 for the fronts and then try and pair it with a 305/35/18 for the rear, only available in the NT555r, it shows no availability.

kbreese

I don't see where it "recommends" any particular tire. You just put in the size you need for front and back and it simply lists what they have available in those sizes. For 275/40/17 front and 305/35/18 rear it lists all of them in those sizes; the regular 555 (front only) and R's and the RII's. Maybe I am missing something?

Last C5

Mmmmmm? Be interesting to give them a call and see what their intent is there.

Bertram65

I emailed Nitto...

My email:
I am interested in running a 275/35/18 tire on the front and a 305/35/18 on the rear on my Z06. The staggered tire size selector lists the front as a NT555 and the rear as a NT555R, is it ok to rum the two different model tires? Any issues with different compounds in the tires or treads?

Nitto's response:
It is very common to use the NT555 in the front and NT555R in the rear of vehicles. This setup improves traction especially in the rear wheels. However the NT555R will wear faster then the NT555. Another suggestion would be to use the Invo with a 275/35ZR18 matched with the 295/35ZR18. We thank you for your interest in Nitto Tires.

Thank you,
Nitto Technical Department

Last C5

I'm not thinking that's not the best advise around. Now they're suggesting running a 260 TW tire on the front with 10/32 tread and a 100 TW tire on the back with 4/32 tread and expecting neutral handling from a vehicle that already tends to understeer? Not going to happen!

Rob Burgoon

Should be fine. If you add grip to the rear, your max cornering speed will still be limited as it was before, by the fronts. Don't try and take corners at higher speeds than you could before, and you should be golden.

jaybar

My replica 427 Cobra came with 245-40-17 Nitto 555's on the front and
315-40-17 Nitto Drag radials on the rear.
I drove the car on the road with no problems. But it wasn't a daily driver. Then I started Open Track on a very short course (Gainesville, FL) and found that in hard braking the fronts would lock up. This did not occur every time but only very hard braking at slow speed. I attribute that to the much harder rubber compound of the front tires. I did not have ABS of course.

Since you don't track you should have no problem.

Rob Burgoon

Makes sense. Sticky tires in back, fronts lock first. If you had the same tires all around they would probably all be close to locking when you braked with the same force.

The big issue is if you had your sticky tires up front the rears would lock first under braking (w/o ABS), and let go first if you exceed the limits in a corner. Not everyone can deal with oversteer.

With stickier tires in the rear, no prob.