Lowered with 265 tyres + spacers = rubbing

[wonkydonkey]

Hello chaps. One of the first matters I'm addressing on my new Z4MR is tyre rub. Although it looks pretty good from a static viewpoint, I have some tweaking to do, and the rear end is my priority.

The car has been lowered on H&R springs, has 265/35/18 tyres (standard tyres are 255 wide [edited from 245]) fitted to the original wheels, as well as a 20 mm wheel spacer each side. This increase in width on each side, combined with the lowered ride height, means that the tyres rub on the wheel arch liners on bigger bumps. This car will be well used on the fast, sweeping roads of Exmoor and Wales, where surprise dips and bumps would cause me issues at the moment.

Looking at the witness marks on the arch liners, it looks like swapping the 20 mm spacers for 10 mm might even be too much. I'd like the wheels to fill the arches well, but I reckon the 265 mm tyres might do that on their own and any wheel spacers might result in rubbing.

Question: Does anyone have personal experience and a definitive answer here?

The extended wheel bolts already fitted mean that I can't just whip the spacers out and see how it looks. My two options at the moment are to (a) buy 10 mm spacers and suitable bolts in the hope that it's a winner or (b) buy standard bolts and run without spacers, at the risk of being disappointed by the narrow appearance. Either way, I risk wasting money, so thought I'd ask for any experiences before I start making my own educated guesses

The fronts are 225 and spaced out, rubbing towards full lock, but that's for another day!

 

[wonkydonkey]

I should add that the rear end currently sits 20 mm lower than the front, so I plan to fit the thicker upper spring pads to reduce that difference to 10 mm, but I still want to be able to hit the bump stops without tyre contact, and that 10 mm height gain probably won't achieve that without addressing the wheel spacing issue.

 

[mr wilks]

Oe tyre size would be 255-40-18 on rears but in reality a 245-40 works fine & doesn't look at all out of place (I have the same on my 224 rears)
I can't see the need for anything over 5mm spacer wise on rears & certainly wouldn't think over 12mm /15mm would be necessary :?
Whatever the springs if you have rubbing off 224s you have the wrong tyre size or too much spacer.
Pics of my ZMR on Eibachs with 245-40-18 Dunlop + 5mm spacer

 

[synthedup]

Not sure where you are based but I have a pair of rear arch lines in the garage along with a set of standard BMW wheel bolts. If your lines are damaged due to the running and want to replace them let me known

 

[wonkydonkey]

[ref]mr wilks[/ref] thanks for your thoughts. It really does look as though even 10 mm would still be too much. Dropping to 5 mm makes me question if it's even worth fitting them, so I may just whip them out and pop some standard wheel bolts back in.

[ref]synthedup[/ref] the liners have rub marks but haven't rubbed through or ripped, but thanks for letting me know about yours. Drop me a message with a price for the bolts though if you like

 

[wonkydonkey]

[ref]mr wilks[/ref] just saw your edit with the pics. Most helpful. I'd say with 265s and no spacers, mine shouldn't look lost in the arches at all. I'll get hold of some standard bolts and see how it looks without the spacers. Thank you kindly.

 

[mmm-five]

I'm running 265/40r18 PSS rears, with no spacer, and the only time I get any rubbing in on very hard/high-speed compressions - never on a public road run...even a vigorous forum run in Wales/Scotland/Lakes.

But mine is only about 10mm lower than standard at the rear on Bilstein B16/PSS10

 

[wonkydonkey]

[ref]mmm-five[/ref] thanks for the info and pics. You're on 40 profiles compared to my 35s, so I'm buying a BIT more leeway there, and once I've got the thicker upper spring pads in I should be measuring 660 mm from the ground to the bottom of the middle of the rear wheel arch. I reckon yours must be very similar to that (and your ride height looks spot on to me). From the rear view I think the wheel sits out just about far enough on yours 8)

 

[RedUn]

What spacers do you have on the front? Just swap one side back to front to see how it looks, obviously don't drive it

 

[wonkydonkey]

What spacers do you have on the front? Just swap one side back to front to see how it looks, obviously don't drive it

I didn't have the front wheels off but the spacers are too big to be of any use to my investigation (they look to be about 15 mm). Otherwise I'd be on board with your suggestion

 

[RedUn]

15mm will fit on the rear, it'll be snug but shouldn't rub, I run a similar setup

More than likely though I'd go to a 10 on the back though and keep the front similar, the track width ratio works better that way.

 

[wonkydonkey]

15mm will fit on the rear, it'll be snug but shouldn't rub, I run a similar setup

The problem is that the rub marks on the wheel arch liner measure about 10 mm across, so it looks like I need to reduce the spacing by at least 10 mm. Once I have some shorter wheel bolts I can have a play about, and will experiment with the front spacers on the rear if they are 10 mm or less. I know stance is really important to some people, and I want it to look as good as possible...just not at the expense of being able to hurl it down a road without whincing on every bump! Too many years of smacking the undercarriage of my dad's Caterham on the road have given me PTSD

 

[RedUn]

15mm will fit on the rear, it'll be snug but shouldn't rub, I run a similar setup

The problem is that the rub marks on the wheel arch liner measure about 10 mm across, so it looks like I need to reduce the spacing by at least 10 mm. Once I have some shorter wheel bolts I can have a play about, and will experiment with the front spacers on the rear if they are 10 mm or less. I know stance is really important to some people, and I want it to look as good as possible...just not at the expense of being able to hurl it down a road without whincing on every bump! Too many years of smacking the undercarriage of my dad's Caterham on the road have given me PTSD

I'm not surprised with the setup now, as you say it's been done to look good not drive well...

I think 10 on the rear would be plenty gives you chance to even the track up a bit then with the front

 

[Argenta]

I never understand why anybody would want anything other than OEM track width. It's always what I aim for with aftermarket wheels etc.
But hey, I'm a design engineer.

 

[wonkydonkey]

But hey, I'm a design engineer.

Snap

 

[RedUn]

I never understand why anybody would want anything other than OEM track width. It's always what I aim for with aftermarket wheels etc.
But hey, I'm a design engineer.

Clearance for suspension and bbk...

Edit to add, hence spacing the rear to keep the right ratio

 

[TomK]

But hey, I'm a design engineer.

Hopefully not one involved with load paths :wink:

Strut brace
Additional gain is that it re-inforces the notorious weak BMW strut towers..

This is quite frankly nonsense. The notorious 'mushrooming' that can affect the strut towers is caused from the impact force of the upper suspension strut mount to the car's sheet metal first, the fact that there may or may not be a strut brace tied in with 3 bolts above it is neither here or there really.
This is why bmw sell 'reinforcement plates' that sit on the underside of the strut tower.
Let's not start a "my job makes me more intelligent than you" willy wave :roll:

 

[Dav the wheel nut]

I'll get hold of some standard bolts and see how it looks

I've got a spare set of standard bolts if you want them just to give it a go. I'm not far from you

 

[wonkydonkey]

I'll get hold of some standard bolts and see how it looks

I've got a spare set of standard bolts if you want them just to give it a go. I'm not far from you

Thanks Dave, but I've got hold of a set now (at least the Royal Mail Delivery Office has, I think!). Will give it a bash this weekend.

 

[abar121]

I never understand why anybody would want anything other than OEM track width. It's always what I aim for with aftermarket wheels etc.
But hey, I'm a design engineer.

Agreed!