385/65 R22.5 trailer tyre and rim replacement on the A8 near Chiemsee: incorrect spare wheel size (315/70) and on-site resolution

On 1 July 2026, MT onroad received an urgent call from a haulage company. A semi-trailer had broken down on the hard shoulder of the A8 motorway heading towards Salzburg, near Chiemsee in Bavaria, Germany. The fleet dispatcher reported a damaged tyre on the 3rd (rear) axle on the right side and requested a spare wheel swap using the wheel carried on the vehicle.

The MT onroad coordinator conducted a structured WhatsApp intake to verify key data:

• Vehicle type: Semi-trailer;
• Axle and side: 3rd axle, right side;
• Trailer tyre size: 385/65 R22.5;
• Initial request: Swap damaged wheel with carried spare;
• Location: A8 motorway direction Salzburg, near Chiemsee, hard shoulder.

Once the exact GPS location was confirmed, MT onroad calculated fixed pricing (€500 net) covering dispatch, demounting, mounting the spare wheel, old tyre disposal, and return journey. The customer approved the terms and paid immediately via payment link. MT onroad dispatched the nearest service partner.

On-site inspection: incorrect spare wheel size & damaged rim

The service technician arrived at the breakdown location on the A8. Upon examining the vehicle, two critical issues emerged:

• Incorrect spare wheel size: Contrary to the carrier's assumption, the spare wheel mounted under the chassis was size 315/70 R22.5 (meant for a tractor unit's drive axle), which cannot be fitted to a trailer requiring 385/65 R22.5.
• Damaged wheel rim: The steel rim of the blown tyre suffered severe deformation, making it unsafe for further use.

Under German Road Traffic Licensing Regulations (StVZO), mounting an incorrectly sized tyre or fitting a wheel onto a damaged rim is strictly illegal due to severe crash and blowout risks. The technician correctly refused to mount the incompatible spare wheel.

Scenario adjustment & fast resolution by MT onroad

MT onroad immediately updated the customer's fleet manager and proposed a swift solution: delivering and fitting a new Semperit 385/65 R22.5 trailer tyre together with a new steel rim.

After approving the supplementary quote (€760 including new Semperit tyre, new rim, and fitting), the customer completed payment via a second payment link. The technician fetched the required wheel components and completed the fitting on site.

Result

Despite the unsuitable spare wheel and bent rim, the entire operation was completed in approximately 3.5 hours from the initial call. At 15:12, the driver confirmed that the work was finished, and the vehicle safely resumed its journey to Salzburg. Total job value was €1,260.00.

Case details

Parameter	Details
Service	Mobile truck tyre service + tyre & rim supply
Location	A8 motorway, near Chiemsee, Bavaria, Germany
Vehicle	Semi-trailer
Damage	Tyre blowout & rim deformation (3rd axle right)
Spare tyre issue	Spare wheel was 315/70 R22.5 (drive axle) instead of 385/65 R22.5 (trailer)
Supplied parts	New Semperit 385/65 R22.5 tyre + new steel rim
Payment method	Two-stage online payment via payment link
Total price	€1,260.00
Outcome	New tyre & rim fitted on site; journey resumed

Privacy notice: Company names, registration plates, exact GPS coordinates, and personal details have been anonymised to protect customer privacy.

Why can't a drive axle spare tyre (315/70 R22.5) be fitted to a trailer (385/65 R22.5)?

Fitting a 315/70 R22.5 tyre to a trailer axle violates vehicle homologation and load ratings. The narrower profile alters axle geometry, overloads adjacent tyres, causes EBS braking errors, and results in immediate vehicle prohibition and heavy fines during BALM/police inspections in Germany.