Our Top Recommended Big Brake Upgrade Kits For Your BMW E30 3-Series
Nobody wants to take the wheels off an E30. Original 15 inch basketweaves are half the reason the car looks the way it does, and the usual advice, that a bigger disc means a bigger wheel, reads like a bill for a set of 17s before you have even bought the brakes. On this car that advice is wrong, and knowing why can save you the price of the wheels.
Below are the kits we would actually fit, from the two brands we stock for big brakes: Tarox in northern Italy and HiSpec Motorsport in Dartford. The full BMW E30 range is on the site if you want to browse it raw.
- The E30 is one of very few cars HiSpec list a compact race caliper against, and it fits a 295mm disc behind a 15 inch wheel
- A smaller 300mm road kit needs a 16 inch wheel, so on this car the caliper sets the wheel size, not the disc
- Almost every HiSpec kit is listed twice, once for the E30 and once for the E30 M3, at the same price
- Two kits are priced below smaller kits in the same range, and both are called out below
What is on this page
- The two brands
- Why the caliper sets the wheel size here
- E30 or E30 M3, and why it matters
- Wheel sizes for every kit
- HiSpec 284mm Billet 4
- HiSpec 295mm RS126-6: a six pot on 15s
- Tarox 310mm 6 pot Sport
- The 16 inch HiSpec pair
- HiSpec 360mm Monster 4 and Monster 6
- If the car is on 17s
- What is in each box
- Every kit compared
- Common questions
- What we would actually fit
The two brands we stock for the E30
Both machine their own calipers from billet aluminium and build every kit for the specific car it is going on. The split on the E30 is lopsided: HiSpec cover the car from 284mm up to 360mm across four caliper families, while Tarox build one disc size for it in two fitments.
HiSpec Motorsport
Machined in Dartford from 6082 T6 billet aluminium, calipers and pistons both. Twenty listings cover the E30, spanning the Billet 4, the Monster 4 and Monster 6, and the RS126-6 race caliper that makes this car unusual. Made to order in up to 28 working days, caliper finished in black, red, blue, gold or silver.
Tarox
Built at the factory in northern Italy. Calipers are CNC machined from European billet alloy and hand assembled, discs heat treated and hand balanced to 0.05mm. One disc size for the E30 at 310mm, listed twice, once for the M3 and once for everything else. Both arrive complete with Corsa pads pre-fitted and vehicle specific braided hoses.
Why the caliper sets the wheel size here
Across most of the cars we write these guides for, minimum wheel size tracks disc diameter almost perfectly. Bigger disc, bigger wheel, and the ladder is easy to read. The E30 breaks it, because HiSpec list a compact race caliper against this car and against very few others.
The RS126-6 is a six piston race caliper built narrow on purpose, for 13 inch to 15 inch wheels. HiSpec put it on a 295mm two piece floating disc for the E30 and state it clears a 15 inch wheel. The road going Billet 4, four pistons and a wider body, needs a 16 inch wheel on a 300mm disc. That is a smaller disc asking for a bigger wheel. Read the disc size alone on this car and you will talk yourself out of the better kit.
E30 or E30 M3, and why it matters
Almost every HiSpec size on this car exists as two listings, one named “BMW E30” and one named “BMW E30 M3”, at an identical price. That is not duplication for the sake of it. The M3 carries different front uprights to the rest of the range, so the caliper and disc are common and the mounting bracket is not. Buy under the name that matches your car.
Four places where the two lists do not line up, so you know before you go looking for something that is not there. The 284mm Billet 4 and both 295mm race kits appear under the plain E30 name only. The 310mm Billet 4 appears under the M3 name only. The two piece 335mm Monster 6, part number HISC-048, is M3 only as well. And the 315mm Monster 4 is a single listing whose own description says it covers the E30 including the M3.
Wheel sizes for every kit
Every figure below is HiSpec’s or Tarox’s own published minimum, not our estimate. The two Tarox figures were looked up from their site for this guide. Read the table by caliper as much as by disc: the 295mm race kits sit at 15 inch while the smaller 300mm road kit sits at 16.
| Kit | Disc | Caliper | Smallest wheel |
|---|---|---|---|
| HiSpec 284mm Billet 4 | 284 x 22mm, 1P | Billet 4, road | 15 inch |
| HiSpec 285mm Billet 4 | 285mm | Billet 4, road | 15 inch |
| HiSpec 295mm RS126-6 | 295 x 28 or 32mm, 2P | RS126-6, race | 15 inch |
| HiSpec 300mm Billet 4 | 300mm | Billet 4, road | 16 inch |
| HiSpec 310mm Billet 4 | 310mm | Billet 4, road | 16 inch |
| Tarox 310mm 6 pot Sport | 310 x 24 or 26mm, 2P | B32, 6 piston | 16 inch |
| HiSpec 315mm Monster 4 | 315mm | Monster 4, road | 16 inch |
| HiSpec 325mm Billet 4 | 325mm | Billet 4, road | 17 inch |
| HiSpec 335mm Monster 4 / 6 | 335mm | Monster, road | 17 inch |
| HiSpec 360mm Monster 4 / 6 | 360mm | Monster, road | 18 inch |
HiSpec 284mm Billet 4: the way in
The cheapest way to a proper four piston billet caliper on an E30, and it stays behind a 15 inch wheel. One piece 284mm disc, 22mm thick, with the Billet 4 caliper machined from 6082 T6 billet aluminium and running external boots to keep the dirt out. Pads and braided hoses are priced separately on this one, so add those in before comparing it against anything that includes them.
- £785.44 inc VAT, pads and hoses extra
- Fits behind 15 inch wheels
- 284mm one piece disc, 22mm thick, four piston Billet 4
- Listed under the plain E30 name, not the M3
- Made to order in the UK, up to 28 working days, five caliper colours
HiSpec 295mm RS126-6: a six pot on 15 inch wheels
This is the kit that makes the E30 worth writing about. A six piston race caliper on a 295mm two piece floating rotor, and HiSpec state it clears a 15 inch wheel, which is smaller than the 300mm road kit asks for. Billet body, billet pistons with stainless inserts, high temperature seals and stainless wear plates. Two versions, differing only in disc thickness: 28mm and 32mm, same price either way.
Garreth’s call on which: the 32mm disc holds more heat before it starts complaining, so take it if the car sees track days. The 28mm is the lighter of the two and plenty for a fast road E30. Pads and hoses are priced separately on both.
- £1,330.80 inc VAT each, 28mm and 32mm the same price
- Fits behind 15 inch wheels, smaller than the 300mm road kit needs
- 295mm two piece floating rotor on billet mounting bells
- Six piston RS126-6 race caliper, radial mount
- Listed under the plain E30 name, pads and hoses extra
Tarox 310mm 6 pot Sport: the complete kit
The only Tarox disc size for the E30, listed twice, once for the M3 with a 24mm disc and once for everything else with a 26mm disc, at the same price. It is the dearest kit on this page by some way and the only one that needs nothing else buying. Corsa pads arrive already fitted, the braided hoses are cut for the car, and the six piston B32 caliper is hand assembled and individually tested in Italy.
Do the sum before dismissing the price. Every HiSpec kit here needs pads and hoses on top, which is usually £120 to £150, so the real gap is smaller than the sticker suggests. It is still the premium option, and on a car you are keeping, we think it earns it.
- £2,094.00 inc VAT, complete, both fitments the same price
- Fits behind 16 inch wheels, looked up from Tarox per kit
- 310mm two piece floating disc, balanced to 0.05mm
- Corsa pads pre-fitted and vehicle specific braided hoses included
- Disc styles F2000, Sport Japan, C83 or D95, five caliper colours
The 16 inch HiSpec pair, and an odd price
Two ways to use a 16 inch wheel. The 310mm Billet 4 is listed under the M3 name only and costs £1,130.00 inc VAT, which is less than both the 300mm kit at £1,464.00 and the smaller 285mm at £1,254.00. Bigger disc, lower price, in the same caliper family. We have checked it against the store more than once and that is the published figure, so we are not going to pretend the dearer kit is the better buy.
The 315mm Monster 4 steps up the caliper instead of the wheel size. The Monster pad is a third longer than the Billet 4’s with more piston area behind it, which is the one to have if the car is heavy on power or brakes hard repeatedly. It is also the single listing on this car that covers the E30 and the M3 together.
- 310mm Billet 4 at £1,130.00, 315mm Monster 4 at £1,489.50, both inc VAT
- Both fit behind 16 inch wheels
- The 310mm undercuts the smaller 300mm and 285mm kits, which we have flagged to the store
- 310mm is listed for the M3 only, 315mm covers the E30 and M3 together
- Pads and braided hoses priced separately on both
HiSpec 360mm Monster 4 and Monster 6: the big pair
The largest discs HiSpec build for the E30, and both want an 18 inch wheel, which is a lot of wheel for a car this size. The pricing runs backwards here too: the 360mm Monster 4 at £1,635.00 is fifteen pounds cheaper than the 335mm Monster 4 at £1,650.00, so if you are already at 18 inch there is no reason to take the smaller disc.
Between the two calipers, the Monster 6 carries up to 63 per cent more piston area for the same pad size, which shows up as pedal feel more than outright stopping distance. On a road E30 the Monster 4 is plenty. On one doing regular track days, the Monster 6 is the one we would order.
- Monster 4 at £1,635.00, Monster 6 at £1,863.00, both inc VAT
- Both fit behind 18 inch wheels
- 360mm two piece discs, curved vane rotors on the Monster 6
- Both also listed under the E30 M3 name at the same price
- Pads and braided hoses priced separately on both
If the car is on 17s
Three kits sit at 17 inch, which is where a lot of modified E30s have ended up. They ladder cleanly: the Billet 4 for a road car, the Monster 4 once weight or power goes up, the Monster 6 for pedal feel under repeated heavy use. Each has an M3 twin at the same price, and M3 owners have a fourth option in HISC-048, a two piece 335mm Monster 6 at £1,671.90 inc VAT.
What is actually in each box
This is where the price comparisons on this car go wrong, because HiSpec’s E30 listings are not consistent with each other. The older HI- listings include EBC road pads, DOT 5.1 fluid and braided hoses. The newer HISC- two piece listings price pads and hoses separately so you pick the compound. That is most of the gap between the 284mm kit at £785.44 and the 285mm at £1,254.00, two kits a millimetre apart on disc size. Tarox include pads and hoses on both their kits, fitted at the factory.
| In the box | HiSpec HISC- kits | HiSpec older HI- kits | Tarox |
|---|---|---|---|
| Calipers | Billet 4 or RS126-6, 6082 T6 billet | Billet 4, Monster 4 or Monster 6 | B32 6 piston, hand assembled |
| Discs | One piece (284mm) or two piece floating | One or two piece depending on size | Two piece floating, balanced to 0.05mm |
| Brackets and hardware | Included | Included | Included |
| Braided hoses | Priced separately | Included | Included |
| Pads | Priced separately | EBC road pads | Corsa pads, fitted |
| Brake fluid | Not included | DOT 5.1 | Not included |
| Caliper finish | Black, red, blue, gold or silver | Black, red, blue, gold or silver | Black, red, blue, green or gold |
| Built in | Dartford, UK, up to 28 working days | Northern Italy | |
Every kit on this page compared
| Kit | Disc | Listed for | Smallest wheel | Pads / hoses | Price inc VAT |
|---|---|---|---|---|---|
| HiSpec 284 Billet 4 | 284mm, 1P | E30 | 15in | Extra | £785.44 |
| HiSpec 295 RS126-6 (28mm) | 295mm, 2P | E30 | 15in | Extra | £1,330.80 |
| HiSpec 295 RS126-6 (32mm) | 295mm, 2P | E30 | 15in | Extra | £1,330.80 |
| HiSpec 310 Billet 4 | 310mm | E30 M3 | 16in | Extra | £1,130.00 |
| HiSpec 315 Monster 4 | 315mm | E30 and M3 | 16in | Extra | £1,489.50 |
| Tarox 310 6 pot Sport | 310mm, 2P | E30 and M3, listed twice | 16in | Included | £2,094.00 |
| HiSpec 325 Billet 4 | 325mm | E30, M3 twin | 17in | Extra | £1,470.00 |
| HiSpec 335 Monster 4 | 335mm | E30, M3 twin | 17in | Extra | £1,650.00 |
| HiSpec 335 Monster 6 | 335mm | E30, M3 twin | 17in | Extra | £1,773.00 |
| HiSpec 360 Monster 4 | 360mm, 2P | E30, M3 twin | 18in | Extra | £1,635.00 |
| HiSpec 360 Monster 6 | 360mm, 2P | E30, M3 twin | 18in | Extra | £1,863.00 |
Prices include VAT and were correct on 15 August 2026. Tarox minimum wheel sizes looked up from their own product pages per kit, HiSpec figures from their published wheel clearance statements.
Common questions
Can I fit a big brake kit and keep my 15 inch wheels?
Yes, and you have three choices, not one. The 284mm Billet 4 is the cheapest route, and both 295mm RS126-6 kits clear 15 inch wheels too, so you can have a six piston race caliper and a two piece floating disc without changing wheels. Diameter is only half the answer though, so tell us the exact wheel and Cameron will check the spoke clearance.
Why does a 295mm kit fit a smaller wheel than a 300mm kit?
Because the caliper is a different shape. The RS126-6 is a compact race caliper built deliberately narrow for 13 to 15 inch wheels, while the Billet 4 is a wider road caliper. The disc is only one part of what has to fit inside the rim, and on the E30 the caliper is the part that decides it.
My car is not an M3. Can I have the 310mm Billet 4?
Ask us. It is listed against the M3 because that is the bracket HiSpec have tooled for it, and the caliper and disc are common across both cars. HiSpec build brackets to order, so the answer is usually about lead time. We will confirm with them before taking the order.
Is the 310mm Billet 4 really cheaper than the 300mm one?
It is, on our store today: £1,130.00 against £1,464.00, both inc VAT, for a bigger disc in the same caliper family. We have flagged it internally because it looks like a pricing error rather than a deliberate discount. If it is corrected, the price on the product page is the one that stands, so buy from that and not from this table.
How long before it arrives?
HiSpec kits are made to order in Dartford, so allow up to 28 working days, and the RS126-6 kits are the more specialist end of that. Tarox kits are built for the specific car in Italy and lead times move through the year, so ask when you place the order and we will give you the current picture.
What we would actually fit
On original 15 inch wheels and a road car, the 284mm Billet 4. On 15s with track days in the diary, the 295mm RS126-6 in the 32mm disc, which is the most interesting kit on this page and the one most E30 owners do not know exists. On 16s, the 310mm Billet 4 while it is priced where it is, or the Tarox 310mm if you would rather buy once and have the pads and hoses arrive with it. Already on 17s, the Monster 4 for the road and the Monster 6 if the car works hard. We would leave the 360mm kits to cars that are on 18 inch wheels for other reasons.
Ring us on 0115 9893488 with your E30’s badge and your wheel size, and say if it is the M3. Working out which bracket your car needs and whether a wheel will clear at the spokes is Cameron’s corner of the business, and Garreth will tell you straight whether the step up in kit is worth the money on the car you have got.