Wednesday, September 07, 2005

Tire selection and fitment for 120/65 and 120/70

Thank you to: Mike Tiltson, Andy Ruhl, Pete et al

Although it was officially suggested that no 120/70/17 tires be fitted to 750cc models, which came standard with hard to find 120/65/17 rubber, the factory chose to increase rake by .5deg on the 1000cc to allow for more commercial tire selection by owners. The reasoning behind this size restriction is contact of the front tire to the radiator(s) under heavy braking or bumps causing damage. Owners have found however that there are a few safe choices to be had in the easy to find and popularly sized 120/70/17 size while others prefer to stay with the original 120/65/17 - pick your poison, so to speak.

RED = Track focused

Here are 120/70 tires known to fit F4 750:
Dunlop D208GP
Metzeler Rennsport
Metzeler Racetech
Michelin Pilot Power **NOTE for Brutale only, contacts front fender - use 120/65 or spacer
Pirelli Supercorsa
Pirelli Diablo
Pirelli Diablo Corsa

Here are 120/70 tires known to NOT fit F4 750:
Michelin Pilot Sport
Dunlop D207RR
Continental Attack

Tires that are known to come in a 120/65 size:
Dunlop D207RR (no longer available - NLA)
Michelin Pilot Sport (NLA)
Michelin Pilot Power
Pirelli Dragon Corsa (NLA)
Pirelli Diablo Corsa
Dunlop D207ZR
Bridgestone BT010
Bridgestone BT019
Metzeler Sportec M-1



Important with the above considerations are the actual tire size vs the sidewall number. Not all 120/65 or 120/70 tires are the same actual size in mm. One method is to measure the actual height change from your old/current setting first, from axle to ground for example, then measure the new tire's actual height from the same location once installed. Make suspension changes as appropriate; for example moving from a 120/65 tire to a taller (in actual mm) 120/70 may require you drop the front height by a corresponding number of mm. Balance the rear ride height to accommodate the front's change to maintain proper geometry.

-JamesC

3 Comments:

At 6:38 PM , Anonymous Jim Bush said...

Since the F4's have an adjustable steering head angle, would it make sense to add a few degrees of rake to avoid the fender/tire hitting the rad on the Brutale? or would this pose other problems?

 
At 10:00 AM , Anonymous Anonymous said...

My F4 had never a 70 fitted and has no radiator damage, but the plastic piece between de rads has been touched by the tyre, supposingly because of soft suspension.
Changing angle or hight of the fork requires adjusting of rear hight, and thus changing handling and steering characteristics.

 
At 10:59 AM , Anonymous Anonymous said...

Dunlop D208RR also comes in 120x65

 

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