D3 F30 20” alloys issues

[Shak146]

D3 F30 20” alloys

Hi guys, owned my alpina for almost 7 months u till selling the previous which was owned for 2 years.

Issue I have the 20” alloys have low profile 30, and shakes the limbs on any pot hole.

Has anyone gone up on the profile. ???

[glennlud]

Yes I have 19s on my D4 it was a wise choice . 20s look nice but there is not enough rubber on these to provide a decent ride and some protection
from pot holes .

[Charles]

D3 F30 20” alloys

Has anyone gone up on the profile. ???

Increasing the profile will, amongst other things, cause problems with speed reading. If my maths is correct then you will be going faster than the speedo indicates. This is because the overall diameter has increased, thus increasing the rolling circumference - meaning that a fixed point on the tyre travels further for each full rotation. This will not be aligned to the expected rotation distance that the car uses to calculate speed.

It may also cause problems with clearance around the arches.

The only surefire way of having higher profile tyres is to reduce the wheel size, which will come with higher profile tyres to maintain the overall wheel/tyre diameter, rolling circumference and speedo calibration

[Metrics]

Agree with Charles, best to source some 19s.

[Toasey]

This is quite handy for working out what wheel and tyre combo is required to maintain overall diameters:
https://alloywheels.com/tyreCalculator

[JohnW]

Generally for Tyre information I’ve found:

Www.willtheyfit.com

The site includes offset (or as they call it overall “poke”) so you can check if hey will fit in the arch, speedo differences etc.
Handy little diagrams too for comparing old and new.

The Continental Data Book has quite a bit of useful tyre info:

https://cdn.ndias.com/DK/_Content/broch ... tabook.pdf

As does the Michelin book:

https://www.maxfinkelstein.com/pdf/catalog/MICHELIN.pdf

A summary for whatever tyres will safely fit on which wheels I have the attached (sorry I only had up to 19”), the chart is quite old.