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Wheelie Bad Ideas: Putting the strangest wheels on a BMW Z4
We're testing some of the most adventurous tyre modifications possible - but will they be genius, or really wheelie bad ideas?
Words by: Andrew Woodhouse
Last updated on 13 January 2026 | 0 min read
We're testing the limits of what's possible with a modification by trying the zaniest tyre options on a BMW Z4. From go-karts to train tracks, let's see how it goes!
Episode One: Can a BMW Z4 run on train wheels?
Have you ever wondered what would happen if a sports car left the open road and ventured onto railway lines? In the first episode of our new YouTube series, Rory takes a BMW Z4, equips it with bespoke train wheels, and puts it to the test.
You’ll get a front-row seat for the full transformation: swapping rubber tyres for steel wheels, tweaking the suspension, and experimenting with traction and braking on the rails. With Top Gear engineer Peter Ross on board, we explore whether a car designed for smooth tarmac can handle such unconventional terrain. The episode covers every step, from modifying Audi-derived train wheels to adapting the BMW so they fit the track gauge, and even adding ballast and a parachute to improve performance. Stand by for surprises, hands-on engineering, and unexpected outcomes as we push what’s possible with a car you could pick up from Autotrader. Whether you’re fascinated by innovative engineering or simply want to see a sports car take on the British rail network, this first episode offers something a bit different. So, if you want to see a sports car behave in a way it was never designed to behave, or you just want to know what happens when curiosity meets engineering, this is the one. Found on Autotrader. Tested in the strangest way possible! Watch the full episode now and stay tuned for episode two.
You’ll get a front-row seat for the full transformation: swapping rubber tyres for steel wheels, tweaking the suspension, and experimenting with traction and braking on the rails. With Top Gear engineer Peter Ross on board, we explore whether a car designed for smooth tarmac can handle such unconventional terrain. The episode covers every step, from modifying Audi-derived train wheels to adapting the BMW so they fit the track gauge, and even adding ballast and a parachute to improve performance. Stand by for surprises, hands-on engineering, and unexpected outcomes as we push what’s possible with a car you could pick up from Autotrader. Whether you’re fascinated by innovative engineering or simply want to see a sports car take on the British rail network, this first episode offers something a bit different. So, if you want to see a sports car behave in a way it was never designed to behave, or you just want to know what happens when curiosity meets engineering, this is the one. Found on Autotrader. Tested in the strangest way possible! Watch the full episode now and stay tuned for episode two.
Episode Two: We put go-kart wheels on a BMW Z4
In this video, Rory Reid dives into an unusual challenge: can small wheels actually outperform big ones?
To find out, he fits the smallest wheels possible onto a BMW Z4, using trailer-sized rims and custom adapters so they’ll clear the brakes. The transformed Z4 instantly grabs attention, looking a bit like a toy car escaped onto the road. The showdown gets even more interesting as Rory pits his tiny-wheeled Z4 against a Lamborghini Urus sporting enormous 22-inch wheels. On the test track, the Urus’s speed and comfort shine, thanks to its impressive size and ground clearance. Yet the tables turn when it’s time for some driving fun. On a wet handling pad, the Z4’s petite wheels let it slide and drift effortlessly, serving up a go-kart feel that brings an undeniable grin/ The verdict? You’ll have to watch to find out. Episode two is live now.
To find out, he fits the smallest wheels possible onto a BMW Z4, using trailer-sized rims and custom adapters so they’ll clear the brakes. The transformed Z4 instantly grabs attention, looking a bit like a toy car escaped onto the road. The showdown gets even more interesting as Rory pits his tiny-wheeled Z4 against a Lamborghini Urus sporting enormous 22-inch wheels. On the test track, the Urus’s speed and comfort shine, thanks to its impressive size and ground clearance. Yet the tables turn when it’s time for some driving fun. On a wet handling pad, the Z4’s petite wheels let it slide and drift effortlessly, serving up a go-kart feel that brings an undeniable grin/ The verdict? You’ll have to watch to find out. Episode two is live now.
Episode Three: We put massive off-road wheels on a BMW Z4
Having already tried train wheels and tiny go-kart tyres, Rory takes things in the opposite direction by fitting huge off-road wheels to a BMW Z4. The aim is simple: turn a low-slung sports car into a go-anywhere SUV.
With the help of engineer Peter Ross, custom extended adapters are fabricated to push the wheels clear of the bodywork, creating a towering, faintly ridiculous machine dubbed the “Zwagon.” A brief shakedown suggests surprising comfort and grip, so the Z4 is taken to Millbrook’s infamous off-road course for a proper test. It doesn’t last long. The suspension fails almost immediately, forcing Rory into a Plan B: buying a BMW 320d Touring on Autotrader and fitting the same wheels. It performs far better — until it too starts to break. The verdict? Big wheels help, but they don’t make an off-roader. One final experiment remains.
With the help of engineer Peter Ross, custom extended adapters are fabricated to push the wheels clear of the bodywork, creating a towering, faintly ridiculous machine dubbed the “Zwagon.” A brief shakedown suggests surprising comfort and grip, so the Z4 is taken to Millbrook’s infamous off-road course for a proper test. It doesn’t last long. The suspension fails almost immediately, forcing Rory into a Plan B: buying a BMW 320d Touring on Autotrader and fitting the same wheels. It performs far better — until it too starts to break. The verdict? Big wheels help, but they don’t make an off-roader. One final experiment remains.
Episode Four: We put Formula 1 tyres on a BMW Z4
For the final experiment, Rory aims higher than ever, fitting Formula 1 slick tyres to a BMW Z4 to see if elite motorsport rubber can transform a normal road car. With standard Pirelli road tyres as the benchmark, the plan is to test acceleration, braking, handling and lap times head-to-head.
After sourcing F1 Academy slicks and fabricating custom adapters, Peter Ross performs some… enthusiastic wheel-arch modifications to make everything fit. The result looks sensational, but early signs suggest stability isn’t guaranteed. Undeterred, the pair head to the track. The results are dramatic. On slicks, the Z4 accelerates faster, stops significantly shorter, slaloms quicker and, most importantly, laps nearly five seconds faster than on road tyres. The grip is extraordinary, though the experience is sketchy, violent and absolutely not road-friendly. The verdict? Formula 1 tyres work astonishingly well, but only in the right place.
After sourcing F1 Academy slicks and fabricating custom adapters, Peter Ross performs some… enthusiastic wheel-arch modifications to make everything fit. The result looks sensational, but early signs suggest stability isn’t guaranteed. Undeterred, the pair head to the track. The results are dramatic. On slicks, the Z4 accelerates faster, stops significantly shorter, slaloms quicker and, most importantly, laps nearly five seconds faster than on road tyres. The grip is extraordinary, though the experience is sketchy, violent and absolutely not road-friendly. The verdict? Formula 1 tyres work astonishingly well, but only in the right place.
So... was this all a wheelie bad idea?
Over the course of this series, we’ve taken a perfectly normal BMW Z4 and asked one simple question: how much difference can wheels really make? From train wheels and tiny go-kart tyres to enormous off-road rubber and full-blown Formula 1 slicks, each experiment pushed the car further away from what it was ever designed to do.
Some ideas worked better than expected. Others failed almost instantly. All of them proved one thing: wheels and tyres fundamentally alter how a car behaves, for better or worse. It’s been ridiculous, educational, occasionally terrifying, and an entirely unnecessary reminder that curiosity, engineering and a bit of bravery can turn even the most ordinary car into something unforgettable. Found on Autotrader. Tested in the strangest ways possible.
Some ideas worked better than expected. Others failed almost instantly. All of them proved one thing: wheels and tyres fundamentally alter how a car behaves, for better or worse. It’s been ridiculous, educational, occasionally terrifying, and an entirely unnecessary reminder that curiosity, engineering and a bit of bravery can turn even the most ordinary car into something unforgettable. Found on Autotrader. Tested in the strangest ways possible.