Should My Steering Pull to the Left?
QUESTION
Hi John,
I have had a few wheel alignments and I feel the car is still pulling to the left. Some mechanics say it's supposed to pull to the left for safety reasons-if one falls asleep at the wheel it won't veer onto on-coming traffic. Is that right? It seems to be worse on some roads more than others. It's a 2011 Hyundai i30. No damage and serviced when due.
Thanks for your help,
Di
ANSWER
Hi Di,
On a flat, level piece of road, the steering should track 100 per cent straight ahead. if it pulled significantly one way or the other there's a problem because you're trying to go straight, it's pulling left - the tyres are caught in the middle of this 'fight' and they would wear out more quickly.
Also, there's no significant benefit to crashing on the left if you fall asleep. Head-on crashes are often 'better' (in relative terms) for you than crashing into a hard, unyielding object on the roadside at the left. (Much worse for the oncoming driver, however...) Only people who never studied physics disagree with this assertion.
However, most roads in Australia are not dead flat. If they were, water would not run off them when it rains. For this reason, they are generally higher in the centre and lower at the edges. They almost always slope down to the left for this reason. Divided roads (like freeways) often slope exclusively down to the left the whole way across all two or three lanes (because it can be very disconcerting to drive over a crown in the centre when overtaking at 110km/h).
That means a little right steering input is generally needed to keep the car straight ahead when there is a pronounced left cross-slope on the road. The amount of input required varies in relation to how much slope there is, and also how fast you're going. The driver feels this as a pull to the left.
The definitive test is: how is the wear on the front tyres going? The front left tyre usually scrubs out faster than all the others (especially in front drive cars like the i30) because it is turning the hardest (and also driving the car forward) during every left turn. (And left turns are overwhelmingly sharper than right turns in Australia - so that front left tyre works very hard.)
However, if both front tyres are wearing unevenly, that's a big, fat red flag that you have a wheel alignment problem.
Another thing to bear in mind is that once you are focussing on this issue, you become very sensitive to feeling every little uneven tug on the wheel. Mostly it just means there's a crown in the centre of the road, and you're steering against that.
Wheel alignment tends not to be something that changes gradually over time. It tends to be damaged by impact. If you hit a pothole, get a wheel alignment. Also, don't steer into the kerb when parking as that is another major way to knock the steering out of alignment.
Hope this helps,
JC
FOLLOW-UP
Just after posting this piece, I got some interesting feedback from David Basha, the National Marketing and Training Manager at Kumho Tyre Australia. (People think tyres are just black, round bits of rubber when in fact they are surprisingly technical.) Here's what David added to the discussion:
"Tyres can also have a slight imp act on a car pulling to one side in conjunction with the crown of the road. As most tyres are developed overseas; they are often targeted towards right-hand-drive markets where the crown goes the opposite direction.
“Although this can be counteracted through wheel alignment, this can cause slight damage to the tyres because they are forces working against each other. As explained by the link below, Kumho has worked hard to try and overcome this issue of pull by reversing the internal structure of the tyre in particular models for the Australian market.
"In turn this affects the conicity and ply steer residual aligning torque of the wheel and reduces the tendency to pull to the left hand side of the road. In short - by reversing the internal structure of the tyre, it balances out the crown in Australian roads.
http://www.kumho.com.au/blog/2012/10/12/kumho-reverse-belt-technology-for-down-under/
"This is why Kumho’s KH17 was ideal to become original equipment on the Australian made Holden Cruze."
- Thanks David. I appreciate your input,
JC