I had a set of Ventus V4 ES H105 225/45/17 on the front about a year ago to replace the stocks. Everything was fine. The car used to stay locked into its path. The faster I went, the more it felt like it was eating up the road. Awesome.

Recently I replaced the oem rear tires because the previous owner over inflated them and put a fat wear stripe right down the middle. I matched the new back tires to the fronts. As soon as put the Hankooks on the back the car changed. It's very hard to keep straight on the freeway. It feels wobbly. Its perfectly balanced and aligned - it doesnt pull to one side. It almost feels like it gets locked into the grooves on the freeway and it gets pulled side to side. Responsiveness is noticably diminished. The steering wheel feels detatched from the wheels. It felt like a slot car before. Now it feels like an Altima at speeds. Dealer set them at 37 psi which felt off. I dropped them to 33.5 and it helped but didnt nearly do the trick. Specs on the tires dont seem to match to this level of performance drop. Dealer also noted a leak in my rear left shock but that was there before I changed the tires. I thought having the tires matching front and rear would help but it doesn't seem so. I see the tread wear on those Potenzas was 140 and the Ventus is 420. Is that the likely culprit?

 

Exactly what size tires do you have on the car, F & R?

It sounds line "tramlining" - a condition where the car feels like it wanders side to side or gets sucked into the worn groove of the roadway. Different tread patterns will handle differently, those on the Ventus may not be well suited to a car like the Z.

Your Potenzas were considered ultra-high performance tires, hence the low tread wear of 140. 420 would suggest those are all season or some lower performance classification. Those are a lot harder than the Potenzas so they may not have quite the grip. They may have softer sidewalls which could also make them feel squirrely compared to the Potenzas.

Did you check to see that the tires are mounted in the proper direction? Looks for "this side out" or rotation direction arrows.

 

when they did your alignment did they adjust your toe

when our cars have to much of toe in , i think toe in
kinda like piegeon toe

this is what it feels like

 

ive experienced the same thing after i replaced my oem tires. ive been through alot of tires and its never felt like when i first bought it. even after i got it aligned and got my volk gt-s

 

"I matched the new back tires to the fronts." you don't mean size matched right? the car is designed to have the rear tires wider then the fronts.

 

No not at all. I matched the make and model of tire. The tires were previously Potenza RE040's in the back and Hankook Ventus V4 ES H105's in the front. Now they're Hankook V4 all the way around.

Rear is 235/50/17 front is 225/50/17.

It's a stock redline enthusiast automatic 2004.

 

They didn't put them on backwards.

If I turn the wheel side to side within my lane at about 80 it almost feels like the shocks are worn out the way it rebounds. However, thats not a logical culprit because this occured immediately after getting new rears. The front's gave me no change in performance. After changing the rears everything went to ****. Could it really be the sidewall buckling under the pressure? They Ventus is rated for a much higher weight than the Potenzas.

"The car wandering side to side" is exacly what I mean. I've felt unbalanced, unaligned, and toed in/out. This is none of those. Somehow the harder I hold the wheel the harder it is to keep straight at freeway speeds. The car has totally lost poise and confidence above 75 mph.

 

Did you ever put the Potenza RE040's back on or did you always use an alternative to OEM?

 

Maybe there is nothing wrong with the car or tires. You just don't like the tires. It happens.

 

always alternative to oem. are oem tires that good? or is the z that picky that it must only have potenzas? lol

 

I'm not sure. A lot of things about this car are very specific, but people here run different tires all day long with no complaints. DavidV is right about not liking them (given the way the car's performing). However, the tires are affecting the car in ways I didnt think were related to tires.

The most frustrating part of the perfomance loss is the detachment from steering wheel to pavement at freeway speeds (80% of my driving). It feels loose now. I used to be tight - I'd have to muscle the car to turn left and right, and it was millimeter precise - locked into position on the pavement. Now it feels "airy" and "delayed." Definitely not good in a car like this. If I give the wheel a quick whip to the left or right then back to center it does nothing but wobble the chassis - hence the "Altima" feeling. With the Potenzas that kinda move woulda thrown me out of my lane.

Obviously if it's just the tires then the easy fix would be different ones. After this experience I wouldn't get anything besides the OEM on the rear unless there's another factor at play here.

 

A couple of possible reasons for the problem you describe:

1. New tires have a “grease” coating that makes the tire feel unresponsive in the way you describe. After a week or maybe a little longer, the tires are “scuffed-in” and handling improves.

2. If the new tires have softer sidewalls (the Potenzas have a stiff sidewall), you notice the difference. Regrettably that does not correct itself, although you may become more accustomed to the different handling with time.

--Spike

 

hmm i didnt know about the hardness of sidewalls differ, thanks for the input.

 

I put Potenza Grids on my rear OEMs and i love them better then my OE Potenzas that the car came with

 

Wait, so you had 225/45/17 upfront and (unknown rear) before, and now you're riding on Front 225/50/17 and Rear is 235/50/17?

I mean, that would seem like the most obvious reason for change in ride feel to me.
Shouldn't you at least be sporting a 245 in the back?

 

+100

 

...wait huh? I'm sporting what the car came with. 225/50/17 front 235/50/17 back - looking at the original window sticker at the moment just to double check. I'm sorry I'm just not sure what you're getting at - I simply swapped tires. Wheels are the original 7 spoke 17" alloys.

Edit: Sorry its late i missed the part where I typed it wrong. It was never 225/45/17 thats a typo they were always 225/50/17 front 235/50/17 back.

 

Are those the G019's with a 460 treadwear?

 

^^ No to the 245 comment.

BlueSQ is correct when he states his OEM tire sizes are 225/50/17 front 235/50/17 back.

Sidewall rigidity does make a noticeable difference in handling, and this is especially true for 17” wheels since the tires have taller sidewalls. I run 17” wheels in the winter months to accommodate my snow tires. The snow tires have a soft sidewall, and they handle very poorly on dry pavement.

--Spike

 

So I am finding other members like jasabeats are running above 420 treadwear. So maybe its not the hardness or the brand but the sidewall. The Z is a heavy car for a two seater, not a flyweight.

Spike100 how did you determine your sidewall rating? Is there a rating on the tire itself?