Prius pulls to the right, can't tell what to do next

I searched and couldn't find anyone with a similar situation. We have an 06 PKG8 Prius with 65k miles. It's my fiance's car and I rarely drive it so I can't say for certain when the issue started, but it was sometime within the past 10k miles.

The car when on a perfectly flat road/highway, pulls to the right pretty severely. If you take your hand off the wheel on a perfectly flat road, it'll be in the next lane within 1-2 seconds.

I basically have to drive the car with the wheel turned 5 degrees to the left to compensate for the pulling to the right, this is at highway speeds, the situation is minimized at slower speeds.

I've checked and repaired the obvious. Tire pressure is 35psi on all four tires and I just had a wheel alignment done. The overall alignment was good, but there was some toe on the front tires that was out of spec, but actually considering the 65k miles, the overall alignment was great.

The pulling is not related to braking or acceleration, it's a constant pull that would happen while coasting on the highway.

I'm just not sure where to go to chase this any further. The car hasn't been in an accident, the tires were replaced about 20k miles ago and have been rotated and pressure is consistent across all four tires.

I know all cars will generally pull especially at this age, but this Prius has started pulling a bit too hard to be normal.

After paying for the computer alignment and not seeing any improvement, I'm really curious as to where to start my next investigation.

Any advice is appreciated.

 

I think the pulling happened after my last tire rotation so I'll definitely try swapping the left and right tires to see what happens.

As far as the alignment, I doubt they did a roadtest, but I'm not sure, I wasn't there. Despite both front wheels being slightly out of toe-spec, the alignment didn't improve the situation, it still pulls hard to the right.

To one of the earlier posts, yes I know all roads aren't flat, but this pulling is crazy severe. I have another car that drives on the same road with no such effect.

I'll start with swapping the tires out to rule out whether it's related to a tire or not.

Thanks,
Brian

 

I highly doubt they did, in fact I'm almost certain. My question on this, is the zero reset just put the wheel back to TDC? Some steering wheels get out of whack but when you let go they return to the off position and drive straight. When I lift my hands off, the wheel does return to TDC, but the car veers to the right. At 65MPH or higher it does so pretty hastily.

I'm going to swap the tires from right to left and see what we end up with. I'm thinking I have a tire issue somewhere. I checked for a dragging caliper and found no evidence of that. I don't think it's bearing related or anything of the sorts.

Could out of balance wheels cause this? I may just ask to have the wheels all rebalanced as they've had these tires for over 25k miles (my BMW tires last 12k miles, these last forever).

 

I'm having the wheels rebalanced and cross-rotated, we'll see how that affects things to rule out a radial-pull. I don't think there's a balance issue since the wheel seems smooth a speed.

I recall the pull coming on shortly after our last tire rotation so I'm thinking it may be that and not alignment. We'll see, I'll check it out tonight on the ride home.

 

Well rebalancing and cross-rotating solved the problem. The car drives dead straight and the overall steering response is better. I can't say with 100% what solved the problem, but since the steering wheel didn't vibrate or shake at speed before, I'm thinking I just had a tire with a slipped belt in it. The problem originally showed up 5k ago at my last service after I had a tire rotation done. Clearly the bad tire shows its signs when mounted on the front.

The tires are the second set and were replaced sometime around 40k. They have another 10-15k left in them so I just plan on leaving them on the rear and not rotating them until I get new wheels. I read that a radial pull doesn't need to changed so long as it isn't causing negative effects (e.g., it won't fall apart on the road). I'll keep watching wear and we'll go from there.

It now drives straighter than my 08 BMW M.