My Ford fiesta 2010 has had an issue for about a year now. In the wet weather my steering wheel will shake and my tyres will be shaking to (not sure if it front or back). This normally happens around 40/45 miles and above. 
 

A list of what I’ve had done the past year:

Inner and outer track rod ends

track rods

steering rack

tracking and balancing of the wheels (multiple times)

 

Very strange! So doesn't do this shaking in the dry then ?

Oh the question needs putting into the main Fiesta section and not guides.

First check that you have the same make of tyres on both sides on each axle, Read the  sides and check they each say something like 185/60r15. This number needs to match on all tyres. Then check your tyre pressures.

An apparently silly question, but it isn't: if the wipers are used, does this happen? You could try by using the screen washer. Sometimes a wiper assembly gets to work loose and can give all sorts of funny vibrations. This check should rule that out.

I had a similar issues with a 2010 Fiesta years ago, but it happened wet or dry. The cause after several attempts at rebalancing was discovered to be distorted alloy wheels, which were a common issue at the time, particularly on Titanium and Zetec S with the larger wheels.

16 minutes ago, Eric Bloodaxe said:

... rebalancing was discovered to be distorted alloy wheels,...

That'll certainly cause the vibration, but I've never seen it differentiate between wet & dry, odd one that...

5 hours ago, Sophie Fletcher said:

tracking and balancing of the wheels (multiple times)

Move the front wheels to the back (both sides) and the back to the front. See if this makes a difference to the vibration/handling.

Sounds like a tyre manufacturing defect, or damage to the tyre side wall.

11 hours ago, unofix said:

Sounds like a tyre manufacturing defect, or damage to the tyre side wall.

Heck! in the late 90's we had a Peugeot 405, out of work for 6 months we took the second hand route for replacement tyres, had two used tyres put on the front but from about 45mph onwards the steering wheel vibrated, we just ignored it, getting a job i decided to go to a tyre garage and get the front wheels balanced and tracking checked, tyre bloke fetched me into the garage and told me to look at the driverside tyre, the tyre lettering was distorted and a big chunk of rubber ripped out, with separation to the rubber, bloke said it's not safe, told him to fit two brand new tyres on the front.

Both of the second hand tyres was defective, both had impact marks which was only visible on the inside, i've never gone the part worn route ever again.

I think we've all come up with some good possible explanations for vibration, but we're still stumped as to why it apparently only happens in the wet. 

I get the feeling this thread is a OPW 😂

On 7/20/2025 at 5:01 PM, Ian Lanc said:

Very strange! So doesn't do this shaking in the dry then ?

Oh the question needs putting into the main Fiesta section and not guides.

No it does unless on the motorway doing 70

On 7/20/2025 at 5:50 PM, anon said:

First check that you have the same make of tyres on both sides on each axle, Read the  sides and check they each say something like 185/60r15. This number needs to match on all tyres. Then check your tyre pressures.

An apparently silly question, but it isn't: if the wipers are used, does this happen? You could try by using the screen washer. Sometimes a wiper assembly gets to work loose and can give all sorts of funny vibrations. This check should rule that out.

I will check that the tyres are the same. I go to the same tyre place, this being ATS euromasters which I buy brand new tyres. They’ve recently done my tyre pressure for me so that should be all good

On 7/20/2025 at 10:15 PM, unofix said:

Move the front wheels to the back (both sides) and the back to the front. See if this makes a difference to the vibration/handling.

Sounds like a tyre manufacturing defect, or damage to the tyre side wall.

I will give this a try. Thankyou

You get the vibrations at 70 in the dry on a motorway and it is worse in the wet, yes? This sounds like it could be a buckled wheel. I would be looking for irregular tyre wear and would jack the car at each corner in turn and then spin the wheel and check for buckling. I suspect that it might be a rear wheel which is why the repeated tracking is not picking it up.

14 minutes ago, Sophie Fletcher said:

I will check that the tyres are the same. I go to the same tyre place, this being ATS euromasters which I buy brand new tyres. They’ve recently done my tyre pressure for me so that should be all good

Hold on.  Your last sentence  raises eyebrows. You should not only be capable of checking and adjusting tyre pressure yourself but should be checking it at least fortnightly. Your car shakes at 70 in the dry and 45 to 50 in the wet. Is that right? Your response was unclear.

Think I have a theory that holds water  which I will offer for discussion. Badly worn rear hub bearing causing the rear drum to bind. When wet, the binding causes it to lose grip earlier and the brake coming on and off would make the steering shimmy. I wonder if there are any odd noises from the back?