Besides the usual misalignment, road surfaces, tire wear and size differences, and air pressures we also found the antisway bar a culprit if its not 'flat'. That is one arm tilted slightly higher than the other. I suggest you disconnect the driver's side, not the passengers, and see if that helps your 'wandering'.
and be sure yur wandering isn't due to different slanting of the road. The typical road is slanted toward the outsides from the high center to drain water, get across that or uneven 'slanting' and the car wants to follow the high side.. and be sure your front track is straight ahead with maybe a mm eacxh side toe-in. and be sure your Fit is square, that is the chassis and wheels have the same wheelbase both sides and square across. Fits aren't noted for particularly square chassis thanks mostly to the rear axle attachment.
good luck.

 

I know it's not the roads because I have driven my 2013 STI on the same roads without issue. I believe more of the issue is the high profile, light weight, and the squishy-vague feel of the tires more than anything else. Tire pressures are equal across all four. I will be getting an alignment when I lower the car.

 

wider tires will wander more as your wandering is more likely a result of following the deviations in the road surface. check your alignment to make sure toe in same on both sides and your chassis is square meaning the wheelbase is same on both sides and square across the track. Fits are not particularly noted to be great in that respect.

 

The 'wandering' is due to a very sensitive rack and pinion steering that is enhanced with power assist.
I personally like the positiveness of the steering. Reminds me of my old Bug Eye Sprite.

 

I have an 09 fit sport. when the stock tires wore out i put some hankook performance tires on they were slightly different size(205) than the stock but very very close.... and it made it wander all over... i had to keep a tight grip on the wheel. I also later put after market wheels on later...slightly wider...and it wandered all over. I did notice that the fit will wander because its narrower than other cars and trucks so one wheel will follow the low spot in the lane and the other one is not..so it would wander because of that too... also .... under a heavy load it would wander a lot... When I went back to the stock wheels and a softer tire... like general gmax it road awesome again... and got better gas milage. I would never consider lowering the car....rather If anything I would like to raise it an inch or so like a rally car for gravel roads.

 

I feel like I have no control over my car. Steering is very light and the swaying/swerving is too much for me. I grip onto the steering wheel tightly because I feel like I have little to no control over the vehicle at highway speeds but in the city? I am god.

 

my shit wanders.

even in park lol.

no but seriously, crosswinds can change my lane.



getting a rear sway bar. will report back if it helps.

 

rsb didn't change the wandering, but i'm a lot more used to the car and wandering isn't really a problem, has more to do with the road than the car i find.

RSB is a must for a base model fit

 

My 09 Fit Sport wandered and on-center feel had the dead band of a cheap video game. Local road quality, EPS, tolerance stack up, tire (I think the Dunlops might be an issue), rear toe (mine was at 5 mm toe in - the factory limit) and the sum of all of this can exacerbate the wonkish feel and generate varying opinions.

Today,out of curiosity I checked toe setting. The front toe was within factory specs (toed out) but tire wear indicated a touch of excessive toe-out. Adjusted toe to the factory toe-in limit (3mm). The crappy steering feel and wandering went away. almost as good as my Cayman S (OK that is exaggerating).

I did the adjustment with a plumb bob, patience and tape measure (metric preferred). If skeptical, you can always DIY to your liking and then find an alignment shop to double check and bias it to the factory limit. The good ones will adjust to a precise setting if requested. You can also check chassis sureness this way.

For the adventurous, this is the movement per tie rod rotation to help you hone in you adjustment.
1 flat (mm) 1.27
2 flat (mm) 2.54
3 flat (mm) 3.81
4 flat (mm) 5.08
5 flat (mm) 6.35
6 flat (mm) 7.62

I have a set of OEM size Michelin's waiting to be installed. I'll update if it adds quality to the car's dynamics.

A good 101 book on suspension set up is Fred Puhn's "How to Make Your Car Handle." It may be dated but still relevant - Fits still have springs, dampers, tires, anti-roll bars, balljoints, tie rods, steering wheels and the big nut behind it. Hope this helps.

Retired old school autocrosser.

 

In the suspension theory thread it talked about lowering the front more than the back so the front wheels pull to center when moving foward. The combo of that and a wider tire help the car feel more stable and planted. I also have wheel spacers I imagine that helps.