DIY

DIY BMW Wheel Refurbishment–Repair Curbed Alloys

Most BMWs are sold with an attractive set of alloy wheels and low-profile tyres.  These look great but few cars escape the dreaded ‘curb rash’  - scraping the wheels on a concrete curb while parking.  This usually starts on the passenger side front wheel but in cars which have been roughly parked it will often spread to all 4 wheels (and sometimes the spare!)

The car in question had the worst set of curbed wheels I have ever seen – all 4 badly damaged 360 degrees of the way around, and some actual missing chunks.  They were ugly wheels and  were bent providing a nasty shudder at highway speeds , so I found some BBS Style 66 wheels off a sports edition.  These are great wheels with different width and offset and really fill out the rear guards.  Unfortunately, you shouldn’t believe everything you read in an online auction ad and when the wheels turned up, not one of them was at a standard I was prepared to put on the car.  All 4 had marks to some degree, both around the rim but also around where the wheel nuts go on, and the center caps were worn and unattractive.   Add to that old adhesive from wheel balance weights and a total refurbishment was required. 

Above : They might look OK from a distance, but up close they are a mess of curbing, scratching and old wheel balance adhesive, and have very dull center caps.

Up close you can see the state of the wheels.  Adding a set of scratched up wheels to your car drags down the appearance.

While there are people who will do this for you and do a good job, I was quoted prices of around $200 per wheel at local wheel places, and decided to tackle it myself.

Materials Required

Refurbishing painted alloy wheels is simple  - it’s just a case of refinishing the painted surface with preparation and new paint .  If you have anodised or another treatment (such as Style 5 or Style 42 wheels) then, unless you want to paint them, you’ll need another technique.

You’ll need the following:

* Sandpaper – 240 and 400 grit wet and dry paper

* Paint thinners for cleanup

* Tack cloth for dust removal

* Masking tape and newspaper for masking

* Scratch Filler/Primer spray can (2 cans for 4 wheels)

* Wurth Wheel Silver Lacquer spray can (2 cans for 4 wheels)

* Wurth High Gloss clear Varnish Lacquer spray can (2 cans for 4 wheels)

* Sanding block and/or Orbital Sander

Wurth Silver and Clear and local auto parts store primer filler (or ‘spray putty’)

Some people recommend wheel putty for filling damage – you’ll only need this if you have seriously deep gouges.  If you have superficial scratching you can just remove enough alloy material to take it back to smooth.

You’ll also need somewhere to create a lot of dust and do some spray painting – well ventilated, warm and with a minimum of airborne dust.

Preparation for Repair

This process uses the wheels with the tyres removed  - it is possible to repair wheels with the tyres in place, but you’ll always do a better job with the wheel ‘raw’.  It doesn’t cost much to get a local tyre place to remove the tyres – you may even be able to get them to hold the tyres for re-fitment if you intend to replace the existing tyres.

Remove the wheel caps and if you’re doing a total repaint, pull out the valves as well.  Valves are cheap so just grab them with a big pair of pliers and twist out.  These particular wheels have a small plastic ‘M///’ badge which I prised off with a razor blade and kept for later.

You should now have a naked alloy wheel.  At this point you should decide if the wheels are true and straight, or if they need work.  You’ll know if they are your wheels whether they have been bent (again, alloy wheels are soft and a bad pothole or curb hit can introduce a bend).  In this case I bought these wheels off the internet of unknown provenance, and the condition was much worse than I expected, so I decided to take them to a local specialist for checking.  He loaded them onto his equipment and looked specifically for out-of-true wheels and other damage.  A couple had minor issues which he corrected – the total cost was around $50 which is quite reasonable for the peace of mind in knowing that the wheels are ready for high speed use (highway speeds only!)

Repairing Curb Scuffs and Marks

The easiest way to repair the scratching on alloy wheels, is to use an orbital sander with the 240 grit paper.  Alloy wheels are quite soft (which is why you can damage them easily in the first place) so just by using an orbital sander you can sand out the scratches.  You will be removing metal so you’ll need to use a gradual motion which follows the rim of the wheel – don’t sit the sander in one spot and dig out scratches – you should be starting well away from the scratches and working in and out with a smooth motion.

For tricky interior/spoke/other locations where the sander cannot be used, use a sanding block or just your finger with paper wrapped around it.  The key is be consistent and work into an area rather than attacking it directly.  You want to work through the existing layers of paint and get down to the alloy, and have a shiny metal surface with no visible scratching.  It should have a dull silver alloy sheen to it.  There is no need to remove paint where the existing paint is in good condition, but you should scuff it to remove it down.  If there are any areas of adhesive from stickers, weights or just tar and mess in general, rub down with a rag dipped in paint thinners.

You have a choice in whether to just refinish the outer rim (as in this example) or the inner rim.  There is no difference in process, but you’ll need more paint if you want to do the entire rim.  In either case you should wash down the entire rim and wipe it down with thinners to remove all old brake dust, dirt and and tar.  You want to have the entire rim extremely clean where you have not been sanding.  The reason for this is to prevent the spray painting process blowing dirt and muck around.

Painting the wheels

Now you’re ready for paint, so start masking up.  I recommend masking even if you do both sides of the wheel, to prevent excessive overspray patterns and blow back – which is more likely in more detailed wheel designs.  Tape up the newspaper so that only the side of the rim you’re painting is visible.  Find a natural ridge to put the masking tape on, and run it around the entire rim.

As a final step before breaking out the primer can, get your tack cloth and carefully wipe over the entire surface of the wheel, picking up any dust, loose material or anything at all.  Cleanliness is the key to good paint.  Put down something to paint on – not just something to capture overspray, but also something to cover the ground so you don’t get dust blown up.

The ‘spray putty’ or primer filler is easy to apply – but be careful about creating a ton of overspray.  Paint in smooth movements around 1/3rd of the rim at a time, and be careful about bumping the base of the can on fresh paint on the opposite side from where you are painting.  If you have something easy to spin a wheel on (a potters wheel would be ideal!) it might be easier.   Despite the name, the paint will only fill the marks from the 240 grit, and won’t fill deeper marks if you have any left.  If you have deep gouges, look for some wheel putty to fill them.

Above : The wheel on the left has been sanded back and masked ready for paint.  The dull grey areas are the factory primer, the factory silver is still visible in a lot of places, and the very lip has been taken back to the alloy to remove the scratches and gouging.  Note the valve, M Badging and centre caps are all removed.  The wheel on the right has been freshly done in the primer filler.

Each different primer will have different instructions on drying time and number of coats required, so follow the instructions carefully. That includes the recommended ‘shake’ time – rattle that can for the required number of minutes to ensure proper mixing.  Leave enough time for drying properly and don’t try and take shortcuts.  The above photo is taken next to a swimming pool because that was the best place I could find with no wind, warm sun and the concreted area next to water cuts down the amount of dust considerably (BMW uses water in the factory spray booths to catch overspray and dust).

When painting, it’s better to do a series of light coats (while wet) than trying to lay the paint on in one go.  You don’t want to develop runs, but at the same time make sure you get good coverage.

Once the primer is dry you need to sand back with the 400.  Leave the orbital in the shed and just use a soft block, like a cork or heavy foam sanding block.  Go gently and sand it back – the ideal is to remove the overspray from the primer, remove any orange peel or runs if you made some mistakes.  Use a dribbling garden hose with the wet and dry which gives a better finish and doesn’t create much dust.  The surface should look and feel like glass – any flaws you can see in the paint at this point will stand out like crazy when the final coat goes on.  The final coat is color only and contains no ‘filling’ or ‘fixing’ properties.  What you see is what you will get.

It’s likely you might take one of the wheels back below the primer while sanding – don’t worry if this happens, just clean it up and lay the primer down again, and repeat the sanding back. You’ll quickly get the idea.

After you have all four wheels finished in primer and sanded back to a glass-smooth surface, you’re ready for the silver.  Repeat the masking process – the prior paint and wet sanding will probably have ruined it.  Make sure they are clean, dry and go over again with the tack cloth to remove every last bit of dust and rubbish, even in all those nooks and crannies which are a part of modern wheels.

Laying down the color is just a case of taking it easy.  It helps to have a contrasting primer so you can see what your silver coverage is like.  The Wurth paints are very easy to use and look great straight out of the can – but only if you take it slowly and don’t get runs and sags.   Read the instructions on the can and follow them to the letter.  All paints are different, and Wurth might change the formula from product to product and year to year. 

Above : All 4 wheels straight out of the silver can.

After the silver first coat has dried sufficiently, I went over with the 400 paper and *very* lightly rubbed it back using wet and dry.  This removed any rough overspray and got the surface glass-smooth again.   Then followed the usual procedure of clean, tack cloth and new coat, and let dry thoroughly (follow the instructions on the can!). 

The final step in painting is putting the coat of clear over the top.  This is quite tricky as with clear you can’t actually see where you have been, so be very methodical and use a pattern so you know when you have painted the entire wheel with clear.  Again, follow the instructions on the can for the best finish.

The clear will finish with a light satin finish (it is not a deep gloss).   Because of the finish I don’t recommend wet sanding and polishing the clear – but you will want to remove some of the overspray if you don’t have a nice smooth finish.  You could use a higher grade sandpaper (1200 or so) or even some cutting polish rubbed onto the wheel to finish it up nicely.  In my case the clear went on without any need to finishing up.

Above : After the clear has been applied over the top of the silver and the masking partially removed.  The Wurth paint gives a lovely factory deep finish and satin shine which is tough to replicate using cheaper paints.

Wheel Centers and Finishing Off

You can purchase new wheel caps – but this is all about doing it yourself, solo style!  So I gently separated the wheel caps by removing the plastic silver ring from the BMW white roundel logo. 

I re-finished the silver rings with the Wurth Silver and clear – just by gently sanding with the 400 paper, cleaning with thinners and spraying on a sheet of paper.

I then polished up the BMW logos using some Meguiars plastic polish intended for shining up dull headlights.  This filled in the scratches and removed the dullness from them nicely.  While there is some corrosion around the edge, this is mostly covered by the silver rings so it isn’t really noticeable.  Compared with the grey plastic and dull logos, it makes a big difference.

The final step is re-assembly of the wheel centres, remove any left over masking tape and give them a quick rub over with some wax to protect the paint.  The final results looks great glowing in the afternoon sun:

Not shown at this stage was sticking the M/// badges back on, which I did with a small amount of suitable high temperature exterior glue.  I wouldn’t recommend using a simple double-sided tape as they need to sit in the indents carefully and are subject to heat, brake dust and millions of rotations.

The final result, shod with new tyes and fitted onto the car look amazing compared to the smashed-up rims it had, and compared to the sad Style 66 delivered after winning an auction.  But the cost of buying used wheels and doing my own refurbishment was much, much lower than the cost of buying as-new wheels – and still well under the cost of a single wheel purchased direct from BMW.

The larger-offset Style 66 wheels really set off the lines of the Touring by filling out the rear arches nicely with a wheel showing some ‘dish’.  As they are OEM for this model, there was never any question of rubbing or requiring spacers to fit.  The Wurth Wheel silver paint finish makes the car really pop in the sun.

Workshop Notes

You’ll need several days to complete this to give the paint enough time to dry properly.  Wheels are subject to harsh conditions so give yourself the time to let the paint cure properly before refitting.   The best results will be had by setting up a good place to paint the wheels, free from dust, in the sun, or at least somewhere warm and dry.  Also seriously consider getting a wheel specialist to at least make sure the wheels are not bent or out of balance before you start – because nothing would be more frustrating than putting in all that work only to find out that the car starts to shake violently when up to speed.

I also sold the old, beaten up wheels to someone locally for $100, which covered the cost of materials.  Ironically the buyer just needed a set of wheels to use while he was getting some of his refinished.  I didn’t think anyone would buy the ugly, scratched and stained 16 in wheels but someone’s trash is always someone else’s treasure.

This is one of those jobs on the car where it makes a huge difference to the overall appearance of the car, and doesn’t take any specialised tools or experience, and only requires a few materials.  Definitely something every DIY enthusiast with a set of curbed wheels needs to get done!

Postscript : While doing this job, I ran out of clear and wasn’t happy with the coverage on one of the wheels.  There was a long lead time on the Wurth clear, so I bought some auto-parts store grade clear.   It came out OK at the time, but several years after this was done, some wheel cleaner was used which left the cheaper paint cloudy.  So my recommendation would be to get 3 cans of clear and lay down as much clear as possible to get good coverage and good depth of coat.