2003 Touring 6-Speed (Stock 18 inch rims). I recently replaced my rear tires with Bridgestone RE760's (245/45-18). Still running Bridgestone RE040's up front (225/45-18). I would guess that the wear on the front tires is about 50%.

With these new tires on the steering seems to be very skittish. The car wants to dart off of center. Overall it feels very unstable, nothing like what its been previously. I actually had VDC kick in on an off ramp coming home and its never kicked in there before and I've pushed through there pretty hard.

So here are the questions.
1. Will mixed tire models do this (RE040 & RE760)?
2. Is it possible that the height is taller than what's marked?
3. How does a taller rear tire affect Toe-In? I haven't had the car on a rack but I could see this behavior as the result of being toed out. Is this possible?
4. Is this just a consequence of the tire design?

Any suggestions or theories would be greatly appreciated. The car is now scary to drive at upper highway speeds (80+).

 

maybe cuz yer fronts are 50% worn? have u checked how even your tread wear is? the rears are the stock size? shouldnt be taller then..


i have this problem but on the rear! and its most prevelant at high speeds 70+. ive heard lower offset wheels can be attributed to this which i have. but i nearly squeezed one out going 85mph on a highway road with my rear end "shimmying" back-forth about 3 times.

*edit* i think u were talkin about the wider tire being taller.. didnt see that heh. not sure about whether it will affect factory toe settings.

 

I had the same problem when the tread on my fronts were getting lower, and when the cold weather came. Being in NJ im sure you know of route 9, well whenever ide be driving i would have to firmy hold the wheel because it would want to follow every little imperfection on the road. In certain parts the steering wheel would go back and forth. I got new tires and it stopped. I run falken 452's though, stock rims and size.

 

Mixing tires gives unappreciable results. Not good or bad but unpredictable.

Tire height is fine.

 

Did you notice this when the weather just recently got cold? Of course the weather change coorelated with my new tires.

If the tires behave this way by design I really don't like it. The RE760 has several solid bands around the circumference, not sure if this is contributing.

If the wheels weren't balanced properly, would this cause the skittishness?

 

sounds like a possible alignment issue. too much rear negative toe will cause the car to waver back and fourth at speed and make it 'darty'. as well as incorrect camber setting at the front will cause them to track, the on center feel to be missing and things like that.

it could absolutely be the difference in the grip/temp profile of the tires.. I am not familiar with either, but the stock tires suck terribly.

 

Your front-to-rear tire ratio is off. The combo of the 50% fronts and the slightly larger new rear tires exaggerates this offset. The VDC thinks the rear tires are slipping when in corners so the slip light comes on a auto-brakes the car. Your only cure for this is to replace the fronts tires, or shave your rears down past 50% .

Many others, including myself have had this issue. It can be dangerous the longer it goes uncorrected. Taking exit ramps at speed are not the place you want this kind of behavior to occur.

GL

 

To be honest I mostly noticed it last winter, or fall when it started to get cold out. I dont have VDC, but had the same problem. I had different from tires until I changed them 2 months ago. Check the pressure also.

 

being cold out with summer tires will cause the vdc to kick in more. summer tires do not have much traction when the temps drop below 70 degrees. drastically reduced grip from most summer UHPs.

 

So here is the update on what has happened. On 10/31 I got RE760's installed on the front to match the rears that were installed. Steering/handling was still not right. Got scheduled up to get an alignment. This shop runs 6 hunter racks and knows how to operate them. Did an alignment check and then performed a 4 wheel alignment. Got dialed into the middle of Nissan's spec (1mm toe / .08 deg). I'll post the before after later, but Nissan didn't align it straight... it was within spec for total toe, but the passenger side was toed in hard which caused my inside passenger to get eaten up.

After getting the alignment the steering/handling was still not right. Felt like I was driving a shopping cart... it was very scary at highway speed. Was way too sensitive to steering input. I thought it was my imagination so drove it for a week and a half this way and let a few other people drive it. Finally gave up and decided to put my old front RE040's (which I kept) and get new RE040's for the rear. I flipped sides on the front so the extreme wear is now on the outside. The car is now handling like it should.

Conclusion: The RE760 should NOT be used on the Z. I believe the tire design with the double strip invokes too much steering response which is troublesome on a vehicle that handles as well as the Z. What I can't figure out is why did this design when put on the rear have such an impact. Ultimately the alignment or mixing of tires did not appear to cause the issue... it was the tire design.

Other thoughts are welcome. I hope this helps someone else.

 

I mentioned before

Mixing tires gives unappreciable results. Not good or bad but unpredictable.

Glad that the new combination worked out for you.

 

Thanks for the comments but I think you missed the point. There isn't a new combination, I'm back on the OEM model tire RE040. Additionally, mixing of tires didn't necessarily cause the issue because when I matched the tires front & rear the issue persisted.

The problem seems to have been the result of the design of this tire.

 

Damn I'm experiencing this too. When I'm driving around 70 mph on the highway, on certain sections, my car gets "thrown" off center...freaked me out when it happened. It happens everytime on certain stretches on the highway. So it's definitely the tires I guess, and nothing wrong with the alignment? I have the stock Bridgestones on front with not much life left and new Kumho ASX on the rears. God I regret buying those Kumhos. Crap I hope it's not the new Kumhos causing this.

 

you can't really complain about poor handling when you have tires that are in need of replacement