Lowering springs vs coilovers: alignment, tyres, the law

In short. Lowering springs drop the car by a fixed amount on its existing dampers; coilovers replace the spring and damper with a matched unit whose ride height, and often damping, you can adjust. Both change the alignment: Tesla's own specification table shows front camber moving by 0.20° and front toe by 0.11° when the car sits 12 mm lower, so plan an alignment after either. In Great Britain a lowered car can pass its MOT, but the springs must locate, nothing may foul the tyres and the headlamps must still aim correctly; tell your insurer, because UK law ties what it pays to what you told it.

Lowering springs, coilovers and the options in between

The spring carries the weight and sets the ride height; the damper (shock absorber) controls how fast the spring moves. How you lower the car depends on which you replace.

Sources: KW, height-adjustable spring kit; Eibach, Pro-Alignment; MOT manual, section 5; BC Motor Vehicle Act Regulations, 7D.01. Table compiled by the Onyx Forged design office.

Lowering springs are the simpler route: the kit's maker chooses the drop, and the original dampers stay. The trade-off is that a damper built for the standard ride height now starts from a more compressed position, so less of its stroke is left before the bump stop. We have no figure to give for any car: the answer is in the spring maker's application list for your model.

Coilovers set ride height on a threaded sleeve, so the drop is chosen at fitting and can be changed later, corner by corner. The damper comes with the spring, valved for it. KW, a suspension maker, dates its first coilovers with an adjustable lowering range to 1995, giving 45 to 85 mm on the VW Golf II and III as an example (KW, technology). The range is set for one model by the kit's maker: it is not a free choice.

Height-adjustable spring kits sit between the two: adjustable lowering on the standard dampers. We do not rank the options: the deciding facts are the drop the parts maker lists for your model, the state of your dampers, and whether you want to change the height later.

What lowering does to camber and toe

Camber is the tilt of the wheel seen from the front: negative when the top leans in. Toe is where the wheels point seen from above: toe-in when the fronts of a pair point towards each other. Continental describes both, and lists lifting or lowering the vehicle among the times to have the alignment done, because it changes the suspension geometry (Continental UK). The wheel alignment guide covers the signs and how often to check.

Suspension arms swing in an arc, so a lower body puts them at a different angle and the wheel tilts and steers differently. Tesla's service manual gives two sets of alignment values for the coil-sprung Model 3: one measured without load, one with 68 kg of ballast. The ballast lowers the car, and the target angles move:

Source: Tesla, Model 3 service manual, wheel alignment (non-performance coil ride heights). Change column calculated by us.

That is about 0.017° of front camber per millimetre on this car, over this range. Do not stretch it to another car or a bigger drop: geometry is not linear. Each target carries a tolerance (±0.45° for front camber), so the table does not say a car 12 mm lower is out of specification; it shows that 12 mm is enough for the maker to publish different targets. A lowering kit usually drops the car further than that. The same page notes that the Model 3 has no dedicated camber or caster adjustment, and Pirelli says very few vehicles have adjustable caster (Pirelli UK). Toe can usually be reset; camber often cannot without extra parts. Eibach, which sells such parts, writes that "changes in the height of a vehicle can affect the alignment of its wheels" and that beyond a certain drop, the car maker's alignment specifications can no longer be reached (Eibach).

What that means for your tyres

Camber wears one edge. Michelin says excess positive camber wears the outer edge, and excess negative camber the inner edge (Michelin France, in French). To give a sense of scale, on a wheel and tyre 650 mm tall, 0.5° of camber moves the top of the tyre 5.7 mm sideways and 1° moves it 11.3 mm (650 × sin of the angle; our calculation). On a lowered car the inner edge is the one you cannot see without turning the wheel.

Toe scrubs the whole tread. A wheel that points slightly off the direction of travel is dragged sideways as it rolls. The sideways slip is the distance travelled times the tangent of the toe angle:

Calculation by the Onyx Forged design office. It shows size, not wear in millimetres: we have no measured link between slip and tread loss for any tyre. Pirelli's own warning gives the order of magnitude: a major misalignment, especially in toe, can wear through a tyre in just a few hundred miles. Continental calls the effect scrubbing and links it to rapid tread wear. Eibach says uneven tread wear is the sign of excessive toe and camber.

So: align after the suspension has settled at its new height, again after any coilover height change, and check the inner edges of the tyres in the first weeks.

Rubbing and clearance

Lowering takes space out of the wheel arch: a tyre that cleared at standard height can touch the arch lip or the liner over a bump or at full lock, and wider wheels, a lower offset or spacers add to it from the side. The guide to wheels or tyres rubbing gives the tests; the offset explainer and the wheel offset calculator show how far a new wheel moves towards the arch or the strut, and the tyre size calculator gives the overall diameter. Spacers have their own rules: see wheel spacers explained.

Onyx Forged does not recommend a size or an offset. The sizes listed for your car are in its documents, and a what size wheels fit my car check starts there.

The MOT in Great Britain

There is no MOT item for a lowered car as such, and the manual gives no ride height limit. These are the items a lowered car can fail on:

Sources: MOT manual, section 5 and section 4 (updated 14 October 2026).

The unsafe modifications the manual names are welded repairs and "modifications likely to affect the roadworthiness of the vehicle"; it does not name cut springs. Past tyre contact is not a defect: only a tyre fouling at the time of the test is. A missing bump stop rubber is not a reason for rejection. The guide to the MOT with aftermarket wheels covers the wheel and tyre items. Owners forget the headlamps: lowering one end more than the other tilts the beam, and a self-levelling system, if fitted, must work.

Insurance: what UK law says, and elsewhere

The Financial Ombudsman Service defines a modification as a change that is not part of the manufacturer's standard specification, and advises checking the policy before modifying and telling the insurer as soon as possible (FOS, 1 October 2024). Its examples name wheels, not suspension; lowering fits the definition all the same.

The law behind it is the Consumer Insurance (Disclosure and Representations) Act 2012, which covers the whole UK. Section 2(2): "It is the duty of the consumer to take reasonable care not to make a misrepresentation to the insurer" (s. 2). The consequence depends on the kind of mistake (s. 5; Schedule 1):

• Deliberate or reckless: the insurer may avoid the contract, refuse all claims and keep the premiums, unless keeping them would be unfair.
• Careless, and the insurer would not have insured you at all: it may avoid the contract and refuse claims, but must return the premiums.
• Careless, and it would have insured you on different terms: the contract can be treated as if it had those terms, an exclusion for example.
• Careless, and it would have charged more: it may reduce a claim proportionately, paying only the share that the premium you paid bears to the higher one.

A question on the proposal form matters: section 5(5) presumes you knew that a matter the insurer asked a clear and specific question about was relevant. Between renewals, the Ombudsman notes, you usually only have to give information when you buy or renew, but your policy terms may require you to report changes; read yours (FOS, misrepresentation).

In the US, Canada and Australia the duty comes from the policy and from state or provincial law, which we have not reviewed one by one. Everywhere, answer the insurer's questions about modifications accurately and keep the invoices.

The rules in the US, Canada and Australia

United States. Ride height is set state by state. Virginia's code is the most explicit we read. Section 46.2-1063 says a passenger car modified "by alteration of its altitude from the ground" must keep its bumpers "within the range of fourteen inches to twenty-two inches above the ground" (356 to 559 mm), measured to the lower edge of the main bumper bar, and that "No vehicle shall be modified to cause the vehicle body or chassis to come in contact with the ground, expose the fuel tank to damage from collision, or cause the wheels to come in contact with the body under normal operation" (Code of Virginia). Pennsylvania's inspection procedure rejects a car whose tyre makes contact with the body or chassis, whose steering stops let a tyre rub, or whose front suspension is lowered with spring shackle kits or blocks (67 Pa. Code § 175.80, (e)(1)(xx), (e)(2)(iv), (e)(3)(viii)). California's Vehicle Code section 24008 deals with clearance, but the official site refused our request that day, so we do not quote it; read it on leginfo.legislature.ca.gov.

Canada. Rules are provincial. British Columbia's regulation 7.091 says a vehicle with a gross vehicle weight rating under 4,500 kg "must have a minimum clearance for all parts of it, other than the wheels in contact with the level roadway, that is no lower than the lowest point on the rim of any wheel in contact with the roadway", and 7D.01 bans driving a vehicle whose suspension can be controlled from inside while moving, unless the car maker fitted the controller (BC regulations). The rim is closer to the road than you might think:

Our calculation (width × aspect ratio). The rim's lowest point is lower still, since the flange rises above the bead seat and the tyre flattens under load, so these are upper bounds. With a 275/30 R20, the lowest point of the rim sits less than 8.3 cm above the road: a splitter, exhaust or sump guard below that edge breaks the BC rule. Other provinces have their own texts.

Australia. Suspension lowering is governed by the national code for light vehicle modifications (VSB 14) and by each state's rules. The government sites that publish them would not load for us on the day we wrote this, so we give no figure. Ask your state transport authority before fitting.

Fitting: what to plan

1. Check the drop listed for your model in the parts maker's application list.
2. Inspect the dampers you keep: negligible damping is an MOT fail on its own.
3. Leave spring compression to a workshop: a compressed coil spring stores a lot of energy. Under the car, raise it and support it on axle stands, never on the jack alone.
4. Torque suspension bolts to the car maker's figure, at ride height if its manual says so.
5. Align after the car has settled, then re-aim the headlamps and check any levelling sensor.
6. Tell your insurer.

If anything rubs, knocks or pulls after fitting, have it checked before you take the car back on the road.

Frequently asked questions

Are lowering springs or coilovers better?

Neither in general. Springs give a fixed drop on your existing dampers; coilovers an adjustable height with matched, often adjustable, dampers. The choice rests on the drop the parts maker lists for your model, your dampers and whether you want to change the height later.

Do I need an alignment after lowering springs?

Yes. Continental lists lowering among the reasons for one, and Tesla's table shows the camber and toe targets moving over 12 mm of ride height. Have it done once the springs have settled.

Will lowering my car wear my tyres faster?

It can, through camber and toe. Michelin says excess negative camber wears the inner edge; Pirelli says a major toe error can wear through a tyre in a few hundred miles. A correct alignment after lowering limits the effect.

Will a lowered car pass the MOT?

It can. The manual has no ride height limit, but fails springs that do not locate, unsafe spring modifications, suspension that fouls, a tyre fouling during the test, and headlamp aim.

Do I have to tell my insurer about lowering springs?

In the UK you must take reasonable care to answer the insurer's questions accurately, and the Financial Ombudsman advises telling it about modifications as soon as possible. A careless omission can lead to a proportionately reduced claim; a deliberate or reckless one can void the policy.

Is it legal to lower a car in the US?

It depends on the state. Virginia requires a passenger car whose height has been altered to keep its bumpers 14 to 22 inches above the ground, and bans modifications that let the body touch the ground or the wheels touch the body. Pennsylvania's inspection rejects tyres that contact the body.

How low can I go in Canada?

In British Columbia, no part of a vehicle rated under 4,500 kg, other than the wheels, may be lower than the lowest point of any wheel rim. Other provinces have their own rules.

Can I just cut my original springs?

The MOT fails a spring with an unsafe modification, and one that leaves the suspension inoperative is dangerous. A spring too short to stay in its seat at full extension is treated as insecure. Use parts made for the car.

Do new wheels change anything once the car is lowered?

Yes: a wider wheel or a lower offset brings the tyre closer to the arch or strut, where lowering has already taken space. Check clearance at full lock and under compression.

If you are planning wheels for a lowered car, you can describe your car and its suspension when you design your wheels; Onyx Forged wheels are designed to JWL/VIA standards.

Sources

• GOV.UK, MOT inspection manual for private passenger and light commercial vehicles: section 5, axles, wheels, tyres and suspension; section 4, lamps (updated 14 October 2026).
• Consumer Insurance (Disclosure and Representations) Act 2012: section 2, section 5, Schedule 1.
• Financial Ombudsman Service: How car modifications affect your insurance cover (1 October 2024); Misrepresentation and non-disclosure.
• Tesla, Model 3 service manual, wheel alignment.
• Tyre makers: Continental UK, wheel alignment; Pirelli UK, wheel alignment; Michelin France, wheel alignment and balancing (in French).
• Suspension makers: Eibach, Pro-Alignment; KW, height-adjustable spring kit; KW, technology overview.
• Code of Virginia, § 46.2-1063; 67 Pa. Code § 175.80; British Columbia, Motor Vehicle Act Regulations, Divisions 7 and 7D.

All pages were read on 16 October 2026.

The Onyx Forged design office.