Changing only two tires

[tophamn]

Most of the the tire wear occurs when you're breaking the coefficient of friction of the tire against the road, during coasting you have rolling resistance and the forces acting on the tire are lower than the forces needed to accelerate a car or stop it.

The front tyres have to STEER the car, too.

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[Porsche-Guru]

This I would advise against to most people unless youre specifically trying to induce a certain type of behavior from your car that you couldn't achieve via suspension settings, aero or weight balance changes.

When tires are mismatched they can cause that axle to behave differently the other.
They heat up at different rates, have different traction breaking points, or behave differently in rain of loose terrain.
Unless you are specifically and intentionally wanting to accomplish this it is really advisable to stick with the same model tire on all 4 corners.

Not really. What you are stating maybe technically accurate; but in the real world normal day to day driving, I doubt any driver would even notice this.
On normal UK roads, with its relatively (compared to state side) moderate summer temperature, do not foresee any issue.

As an example, look at any tyre comparison website; and the difference in each test (Traction, steering feel, grip levels, break away, wet stopping distances, dry stoppimg distances, lateral grip, cornering, etc…) between the top 3 or 4 reputable tyres is less than 5%.
So, having mixed tyres will at best give a minor difference in normal day to day driving. I doubt most Taycan drivers on the road are even driving at 7/10ths…
Track is a different matter altogether - and your recommendation absolutely stands.


——-
Update: I would definitely have gone for the same make/ model across 4 tyres; but since tyre availability was an issue, I had to do with what was available.
My point is that it is not a make/ break situation in daily driving, if the front/ rears tyres are not even.

 

[Mad Matter]

Not really. What you are stating maybe technically accurate; but in the real world normal day to day driving, I doubt any driver would even notice this.
On normal UK roads, with its relatively (compared to state side) moderate summer temperature, do not foresee any issue.

As an example, look at any tyre comparison website; and the difference in each test (Traction, steering feel, grip levels, break away, wet stopping distances, dry stoppimg distances, lateral grip, cornering, etc…) between the top 3 or 4 reputable tyres is less than 5%.
So, having mixed tyres will at best give a minor difference in normal day to day driving. I doubt most Taycan drivers on the road are even driving at 7/10ths…
Track is a different matter altogether - and your recommendation absolutely stands.


——-
Update: I would definitely have gone for the same make/ model across 4 tyres; but since tyre availability was an issue, I had to do with what was available.
My point is that it is not a make/ break situation in daily driving, if the front/ rears tyres are not even.

I'll agree with you that most people wont notice on everyday driving but when it matters most is when tire choice becomes important. Like having to perform an evasive maneuver because a vehicle lost control in front of you or wildlife crossed the road and your tires are not in sync with each other because it may be too cold or one end want to stop in the rain but the other has yet to channel out the water during the rain. This is when it matters most. Most drivers will never put their car on a track but we have all experienced on the limit driving at some point.

 

[Porsche-Guru]

I'll agree with you that most people wont notice on everyday driving but when it matters most is when tire choice becomes important. Like having to perform an evasive maneuver because a vehicle lost control in front of you or wildlife crossed the road and your tires are not in sync with each other because it may be too cold or one end want to stop in the rain but the other has yet to channel out the water during the rain. This is when it matters most. Most drivers will never put their car on a track but we have all experienced on the limit driving at some point.

I won't argue further.... but I think that the margins are so minimal that even same brand tyres will have different wear after 5,000 miles and would be subject to the same issues you describe.
Even same brand tyres after some wear will behave with the different characteristics that you describe. Staggered tyre sizes, widths - there are already so many variables even for same make/ model tyres.
If this was actually such a big and reported *safety* issue; we would be seeing a lot of this information and regulations in place to ensure that all 4 tyres have to be changed at the same time and all 4 tyres have to be identical.

 

[CliffordJoseph]

Hi all,

I've been wondering this and haven't been able to find a reputable answer.

My car needs new tires. I am considering replacing only the fronts at this time. I cannot see any reason why that wouldnt work but who knows what the Taycan computer thinks.

The fronts are at 15% and wearing unevenly. However the rears are at 50% and wearing very nicely. Now, in a typical awd car, you have to replace all four tires because there is a mechanical driveshaft which requires the tires to be very close in overall diameter to avoid catastrophic damage. However this doesn't exist in the Taycan.

bit of math: The overall diameter of a brand new 265/35R21 vs a 305/30R21 is very close, 712mm vs 709mm, about 0.04% different. However my current setup with near bald fronts and juicy rears definitely has much more variance than that.

I am not interested in arguments aligned to the basic idea of 'just replace them all to be safe' as that's an obvious answer. The question is whether or not I risk physical damage by replacing the fronts before the rears. Please let me know your thoughts

Hi there. What did you end up doing? I am pretty much where you are. My front have 5” tread and my two new back tires will have 9”. I had to replace a punctured tire from road debris. If you only had two replaced, does it drive differently?

 

[blame.latitude]

Hi there. What did you end up doing? I am pretty much where you are. My front have 5” tread and my two new back tires will have 9”. I had to replace a punctured tire from road debris. If you only had two replaced, does it drive differently?

I replaced the fronts only. I put on Eagle F1s. It made no difference to the way the car drives at all. You cant even tell.

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