Alloy wheels are a coveted accessory for many car enthusiasts. Their lightweight construction and sleek styling can make any car look more modern and sporty. However, their intricate designs also make them more susceptible to cracks and damage from everyday driving hazards. As an alloy wheel owner myself, I’ve dealt with my fair share of curb rash, pothole blows, and even cracked rims. But before you resign yourself to an expensive replacement, you may be wondering – can you actually repair a cracked alloy wheel?
The material used to manufacture most alloy wheels is aluminium mixed with small amounts of other metals like magnesium, silicon, and zinc. This makes them lightweight while still maintaining strength. However, aluminium alloys can still develop weaknesses or flaws during the casting process. Manufacturers aim to catch these defects through X-ray testing, but some may still slip through quality control. Over time, these weak spots lead to cracking from the stress put on the wheels during normal driving.
But casting flaws aren’t the only reasons you might end up with cracked alloys. The most common causes of wheel damage include:
Hitting potholes, manholes, curbs, debris or other obstructions in the road puts extreme stress on alloy rims as they take the brunt of the impact. Even minor scrapes can weaken the structure and cause cracks.
Under- or over-inflated tires place more stress on the wheels during driving. Low pressure causes excess flexing while over-inflation leads to reduced shock absorption. Maintaining the recommended tire pressures greatly reduces wheel strain.
Some alloy patterns like multi-spoke wheels have interconnected hollow pockets behind the spokes. Cracks tend to form at the thin joints between these pockets. Solid-faced alloy rims don’t contain these weak points.
While a few hairline cracks may seem harmless at first, they can quickly propagate and expand into more significant fissures. That’s why it’s important to address any cracks or flaws early before they jeopardize the wheel’s structural integrity.
Not all alloy wheel damage is repairable. To determine if your cracked rim can be fixed rather than replaced, consider these key factors:
Single hairline cracks less than 2 inches located between spokes can usually be repaired. Longer cracks or clusters of multiple fractures concentrated in one area make repairs more difficult. Any cracks on the inside barrel of the wheel must be addressed as they affect air retention.
Bends, fractures extending to multiple spokes, and cracks wider than 2mm may indicate excessive structural weakness. At this point, the alloy has likely lost too much integrity to repair. New loads put on the damaged area during future driving could lead to sudden and catastrophic failure.
Cosmetic repairs may be acceptable on rear wheels where appearance doesn’t matter. But any cracks on front facing wheels should be visually undetectable after repairs for aesthetic reasons. Also consider whether the wheel will see continued rugged use or mainly highway miles.
For reference, here’s a simple overview for deciding between repair and replacement:
Now let’s take a closer look at how cracked alloy wheels can be repaired by an experienced technician.
Various methods exist for repairing cracks, gouges, holes and other damage to alloy wheels. The options differ based on factors like crack width, desired cosmetic finish, and shop equipment. Common repair techniques include:
Filling cracks with molten welding rod material provides permanent structural repairs. This works best for hairline cracks no wider than 2mm. Two types of welding may be used:
Of the two methods, TIG welding provides better looking and typically stronger repairs. It fuses the aluminum alloy together nearly seamlessly when done properly. MIG welding suffices for rear wheels or where some cosmetic imperfections are tolerable.
For larger cracks or heavy damage, additional aluminum can be applied over the repair area and machined down to reinforce weakened metal. This adds thickness and strength. Technicians may also straighten moderate bends in wheels using heat or hydraulic pressure before welding.
Liquid plastics effectively close small holes or surface level cracks by filling them from behind after welding. When hardened, the plastic is sanded and buffed flush with the rim. Filler provides supplemental support and an improved cosmetic appearance.
The last steps involve applying body filler, primer and paint to any repair areas so they blend with the existing wheel finish. Some wheel repair shops can also highly polish the surface to a chrome-like mirror shine if desired.
In total, the process aims to permanently re-forge cracked areas while making them visually undetectable unless closely inspected. This requires an overlap of welding techniques, reinforcement methods, finishing skills and artful paint matching. Not all wheel repair shops offer such comprehensive services.
While DIY videos make some wheel repairs look straight-forward, extensive damage should be left to professional alloy wheel technicians. Their experience working with these materials along with proper equipment generally makes for longer lasting, safer and better looking repairs. Consider taking your cracked alloys to a shop if they have:
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Technicians use specialty tools like heat treatment ovens, tig welders, hydraulic presses and precision machining tools to ensure robust repairs and excellent cosmetic refinishing. Most alloy wheel specialists have repaired thousands of cracks enabling them to expertly judge integrity and match finishes. They can also provide future recommendations for protecting the wheel against added damage.
In contrast, amateur home welds and patch jobs may temporarily close cracks and improve appearances. But they rarely restore the original strength compromised by fractures and damage. The inferior repairs often fail again under continued driving stresses leading to the need for eventual replacement.
You can expect to pay around £70-150 per alloy wheel for professional repairs including all welding, reinforcement, painting and finishing. While not inexpensive, it extends the life of your existing wheels at a fraction of the £200+ cost for one new replacement alloy.
Let’s look at a cost comparison based on a typical passenger car with 18” alloy wheels:
Replacing all four alloy wheels could cost anywhere from £720 for basic aftermarket rims all the way up to over £2000 for top-shelf dealer supplied wheels!
Having one or two repaired would only run you £140-300. That’s quite a bargain considering replacement costs. Even if the other two are unrepairable, you still save money by having the salvageable ones fixed.
The only exception might be if you wanted to upgrade to larger diameter or wider custom alloys that require all new wheels anyway. In that case, repairing the old ones offers minimal benefit.
But before resigning your wheels to the scrapyard and shelling out for shiny new rims, always consider repair options first. There’s a good chance you can save them to roll many more miles down the road.
The best way to avoid cracks and costly alloy repairs or replacements is preventing damage in the first place. That comes down to proper maintenance and driving carefully to minimize wheel impacts.
Ensure tires remain inflated to recommended pressures. Low PSI causes excess wheel flexing while over-inflation reduces shock damping on impacts.
Periodically check rims for any new scrapes, cracks or dents before they grow larger. Use touch-up paint on small cosmetic flaws.
Take alternative routes to bypass severely potholed roads which are prime locations for bent and cracked rims. Slow down over railroad crossings, speed bumps and construction zones.
Even minor bends from curb nudges can be re-straightened. This prevents further structural fatigue and damage. Some tire shops offer re-truing services for mildly bent wheels.
Stay proactive with basic maintenance and handling care to minimize alloy wheel cracks. But should you damage one beyond simple scratches or scuffs, remember professional repairs are possible at a fraction of replacement costs. With the proper repairs, there’s no reason a cracked alloy wheel should end up in the recycling bin.
So before consigning your cracked alloys to the bin, consider that repairs are very achievable in many cases. With some expert welding and reconditioning, they can roll smoothly for many more miles. Saving hundreds or even thousands of pounds makes alloy wheel repair extremely worthwhile in most situations.