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Conversion to 10 inch front & rear - at SIP Scootershop

With original 8" or 9" tyres, potholes become pitfalls, you sit up in bends and the Vespa flutters at high speeds. A conversion to 10" tyres brings a significant improvement here. Conversion forks, conversion rims or brake drum conversion kits are the solution here.

The first generation Vespa models ride on small wheels and long for a conversion to 10".

The following rims are original on the first Vesps:

9 inch closed rim

Vespa 50 N/L/R ->V5A1T

9 inch open rim

Vespa 50 R 752189->/V5A2T/V5A3T

8 inch closed rim

Vespa 98/125 V1-15/V30-33/VU /VM/VN/VNA/
Hoffmann/VNB/ACMA /150 VL/VB/VBA/VBB

8 inch open rim

Vespa 125-150 Super/P150S

All can be converted to 10" with conversion rims and conversion steering columns. Brake drum conversion kits are also available for some of them.

Conversion rim 8" to 10"

Closed: Vespa 98/125 V1-15/V30-33/VU /VM/VN/VNA/Hoffmann/VNB/ACMA /150 VL/VB/VBA/VBB
Open: Vespa 125-150 Super/P150S

Perfect for converting a scooter from 8" to 10". The larger tyres stabilise the scooter's straight-line running and make it less susceptible to potholes or other bumps. The larger diameter (10") increases the overall gear ratio on 8" Vespa models. The standard tyre size is 3.50-10". This means that the gear ratio is approx. 10 % longer compared to original 8" wheels. This means lower revs and higher top speed. Ideal for lightly tuned engines, but also originals can easily climb hills with these wheels.

Advantage: Part GS look and easy mounting

The SIP brake drum also allows effective tuning of the brakes.

SIP TIP: With the SIP rim you can enjoy the tubeless rims. Stable handling, improved concentricity and more safety.

Conversion rim 9" to 10"

Closed: Vespa 50 N/L/R ->V5A1T 752188
Open: Vespa 50 R 752189->/V5A2T/V5A3T

The first 50s were fitted with 9" tyres. These are quite tippy, smear away quickly and are not exactly confidence inspiring on tuned scooters or in medium lean operation. Converting to 10" is a simple and significant improvement in riding safety and feel.

The larger diameter also lengthens the overall gear ratio. The standard tyre size on most 50 cc Vespas is 3.00-10". This makes the gear ratio about 8% longer than original 9" wheels. This means lower revs and higher top speed - ideal for lightly tuned Fuffies, but even original Vespa 50s still pull up hills easily with these wheels.

The one-piece SIP aluminium rims have a noticeably better concentricity due to higher manufacturing precision. This makes the handling much more stable.

Drum brake conversion kit from 8" to 10" tyres

Front: Vespa 125 V30-33/VM/VN/VNA/VNB/ACMA/Hoffmann C/Super/150 VL/VB/VBA/VBB/Super/P150S
Rear: Vespa 125 VNB4-6T/Super/150 VBB2T/Super/P150S

The brake drum conversion is a common and proven 8" to 10" conversion. The conversion for the front is relatively easy to implement. Only the dust cover supplied has to be riveted onto the suspension arm with a little effort. It is also suitable for models with a 1-hole brake shoe mount.

At the rear, the brake drum, dust cover and pads are replaced. However, only for models with a 2-hole brake shoe mount. Except for the front dust cover, all supplied components fit Plug&Play.

Advantage: Braking effect of the 10" models.

Which tyres should I use?

By changing the tyre dimension, the gear ratio can also be changed very quickly and easily. With the right engine power, higher speeds can be achieved. Pay attention to the correct width. We recommend tyre sizes 3.50-10 to 90/90-10.






88.9 mm

1154 mm


76.2 mm

1235 mm



88.9 mm

1307 mm



90 mm

1237 mm



90 mm

1265 mm


Further conversion options to 10"

Conversion steering columns

The conversion allows the use of all 20 mm GRIMECA disc brakes. In addition, the vehicle now stands on a solid 10" chassis with a wider range of tyres with the required speed index. The steering column fits into the frame without modification. However, the mudguard mounts have to be adapted on all models. A Vespa PK50-125/S/SS/XL/Automatica steering column serves as the basis. Steering tube height, fork shaft and steering stop have been adapted to the respective models. The slot or hole for the steering lock must be adapted to the tolerances on the vehicle itself.

Engine PX in Oldi or PK in V50

If you install an engine of the younger generation in your oldtimer, you will of course have the side effect of converting to 10 inch rims. In such a case, you only have to worry about converting the front wheel. We have not yet listed individual engines or crankcases in this chapter.

Customers ask - SIP answers

"What else do I need to change on the frame when converting from 8" to 10" rim?"

For 10" conversions with rim and brake drum kits on 8" Vesps, it is essential to use harder springs, as this can cause the mudguard to drag. If you use conversion forks, you must adapt your mudguard to them. Otherwise the kits usually fit plug & play.