I recently converted my P400 from 20 to 18" rims and noticed after some trips in the mud that I'm seeing some small grooves on all 4 rims. Very shallow. I expected some given the tight clearance and muddy terrain that I've been planning on visiting. Front right where no brake mods other than removal of the mud-scraper was done has the worst damage. I want to say ~0.5mm deep by 2mm grove has been carved by a rock between the front caliper and the rim.

I knew this was a risk factor associated with the change to a smaller rim but had figured it would be the rears where the clearance is tighter, 2-3mm following the caliper trim, versus the front where there is a more normal ~5mm I guess.

It would seem, a smaller gap prevents bigger pebbles getting lodged.

I don't think the groove is deep enough to compromise the integrity of the rim but wondered if others, having done a similar mod to their P400/D300 had noticed anything similar on their rims.

What is the thickness of an alloy rim in that internal area? anyone know? I've been googling to no avail. I know it will vary from rim to rim of course but figured there was a typical range. I'll touch base with Tuffant and see if they have the specs. I'm hoping there is some 4-5mm of Aluminum there.

 

I have a P400 with stock 19" rims and the same thing happened on both the rear rims though not quite to 0.5mm. I seem to remember reading a couple of cases where a rim was destroyed before the rock or pebble freed itself.

 

Yes I saw something like that on FB where they were on an long trip in Australia and a rim split. Another user on here had it happen to them.

The tolerances on the 19"rims is very close on the rear calipers also.

I was just wondering if this is a normal consequence of muddy off-roading fun. Some grooving of the rims.

Thanks very much for chiming in with your own experience. I guess my thread title is a little too specific. Hadn't thought of the 19"s

 

Haven't looked at the exact clearances of a P400 with 18's. Curious if you could fabricate something akin to the wheel scrapers used on rally cars. Metal mount with replaceable silicon or plastic material the remove snow/mud/etc.

Of course, if the wheels are simply too close to the caliper (after grinding or replacing with the smaller caliper), that's a different story...

 

They're close. Real close.

OEM on 20"s comes with a mud scraper on the fronts. This scraper is not on the OEM 19" setup. Its removed to fit 19's or 18's. It's a close fit with 18"s.

Curious if other members of the "P400 rollin' on 18"s club" have noticed anything similar on their rims.

As I said. I was watching the rears closely. Turns out the fronts are the ones taking more of a pounding.

Switching back to my 20s for my winter rubber soon. I'll snag some pictures of the damage then.