What causes "tramlining"?

[Jim 5]

The aftermarket rims (or the tires)on my BMW make the car want to steer itself, especially if there are tire grooves worn into the pavement (the road isn't new and perfectly flat).

Is it the fact that the offset on the rims is perhaps a little different? Or is it the tires?

I have read that certain tires are more susceptible to tramlining, especially z rated tires.

Can anybody advise? I am in the market for new z rated tires.

 

[moribundman]

In my experience, tread designs with wide grooves acerbate the problem, especially in case of directional tires.

 

[Dominic]

Wide tires with a lot of circumferential grooves tend to tramline more than those without the grooves. Good example of this is an old goodyear F1 vs a new F1 GS-D3. Like I said though, it's more common in wide tires (245mm and beyond).

 

[Jim 5]

Interesting,

Thanks,

Currently, the car is shod with Toyo T1-S z rated tires, which are a directional tire.

I have read a few places that these suffer tramlining, but I didn't understand why.

I am going to research this in particular when buying the next set.

 

[Quattro Pete]

Sidewall stiffness also affects tramlining. Basically, a soft sidewall will flex itself more and help absorb the road grooves while very stiff sidwall will not be as compliant and you will feel it on the steering wheel - you'll have to hold the steering wheel tighter to prevent the car from following the grooves.

Now of course the lower the profile, the stiffer the sidewall, and very often, the higher the speed rating, the stiffer the sidewall. But even in the same size and similar speed ratings, two tires can behave very differently. For example, I had two sets of 225/45/17 tires on my old A4: Bridgestone S03 (W-rated), and ContiSportContact2 (Y-rated). The S03 is known for having extremely stiff sidewalls - most of the time you feel like you're riding on rims with no tires at all, and they sure tramlined a lot. On the other hand, the CSC2 was much softer, more comfy, and practically did not tramline at all.

I also do not agree that a tire with a lot of circumferential grooves results in tramlining. CSC2 has a lot of circumferential grooves.

 

[Tosh]

I would say the different offset wheels add to the problem of the new wider(?) tires. In effect, you have changed the alignment. Perhaps an alignment specialist could readjust to compensate?

 

[Russell]

What 245x45x17 tire would tramline the least.

I need to know as I am going to install them on my bmw with factory wheels 8jx17 et20 offset. They will replace 7jx15 et20 offset.

Considering Bridgestone Turanza with Serentiy technolgy or Michelin Exalto AS tires. Any opinions?

 

[Russell]

Sorry, actually 234x45x17 tire size. Wish there was an easy way to edit.

 

[Master ACiD]

i think tramlining is more a function of steering geometry than tyre design. all cars and tyre combos tramline to some degree.
i think it has to do with how far the centre of the wheel is positioned behind the kingpin.

 

[Quattro Pete]

Russell, either one of these tires should be relatively tramline-free. All-season tires don't have very stiff sidewalls.

Also, if the roads near you are pretty smooth, you won't notice any tramlining, even if the particular tires are susceptible to it. When I was driving in northern Virginia, tramlining was a non-issue with my S03s. Then I took them to Poland - welcome to tramlining h-e-l-l.

 

[rpn453]

I've only had tramlining problems when using different tires on front than back.

My 205/50R17 Z-rated Michelins don't tramline any worse than the slightly narrower V-rated Goodyears they succeeded (also 205/50R17, but 1/2" narrower tread), nor the 205/55R16 T-rated Coopers I run in the winter. So I wouldn't blame it on speed rating or sidewall stiffness. Offset and width may affect it. What offset are those aftermarket rims?

I'm using Michelin Pilot Sport A/S right now and they're about as good as it gets for an all-season tire, IMHO.

 

[Quattro Pete]

rpn453, but the Michelin Pilot Sport A/S is still an all-season tire (like you noted) and has a relatively soft sidewall compared to some max performance summer tires out there.

I still stand by my initial statement that tramlining has a lot to do with sidewall stiffness.

 

[rpn453]

QP, I agree that sidewall can have an effect on tramlining, and I suppose it is probably the first thing to check into, but I just didn't think it, by itself, would cause a dramatic enough effect to warrant concern. The easiest way to check if it's due to sidewall stiffness would be to drop some tire pressure and see if it improves.

 

[benjamming]

Quote:

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Sorry, actually 234x45x17 tire size. Wish there was an easy way to edit.

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Edit function work-around

 

[Dominic]

If it has anything to do with alignment, it has mostly to do with CASTER and a little bit to do with toe. Caster is extremely important for steering-wheel centering ability.