Ciao Rotti,

yes the GTB with the GTO rims have a look very nice!!
I agree that the GTB tyres on the GTO rims look terrible because of the rims stick out due to being wider than the tyres.
As per my knowledge, I think your dealer think wrong, for me you can install the GTO tyres without problems.

GTB tyres size : F 245/35/20 - R 305/35/20
GTO tyres size: F 285/30/20 - R 315/35/20

The difference between the two rear tyres width is only 10 mm (+3.3%), difference is little but sure GTO spec tyres will have more grip instead of the standards, than will be reduced the work of e-diff.

Other example is the 575, standard 575 have 295/35/18, more owners have installed the HGTC rims with 305/30/19 without any problems of traction control, also if this traction control is little bit older, but not more!

When i purchased my HGTC she had Bridgestone RE050A, from two years I installed P0 Corsa with the result to have better grip and better handling.

Try to think another another way, than you can't install winter tyres because traction control will be potentially cause inadvertent activation ???
Or you can't change tyre brand because the eventual different grip factor will be potentially cause inadvertent activation ???
.......Crazy.....

For sure other members with more knowledge of me can advise you in a good way....

Best Regards

Fabio

 

Thank you for your info! Did you have 285's on the front and if so did the increased tendency for oversteer cause you problems on the road?

 

Your dealer is completely wrong if that is exactly what he said. The ABS and stability control only care about tire diameters and the relative diameters front to rear, not wheel or tire width. I would actually recommend you use F12 K2 MPSS tires in 315/35 20 on the rear instead of the GTO tires, which are K1 and have less tread depth when new. You do not need the big fronts from the GTO, 285/30 20, because they may cause too much oversteer by sticking too well up front. The GTO has different suspension settings and components than the GTB, balanced for those huge front tires. Either the 245/35 20 fronts from the GTB or the 255/35 20s from the F12 should work fine. Fabio is correct that the difference in diameter (and thus rolling circumference) between the 305/35 20 (28.41", not available in MPSS) and 315/35 20 (28.68") GTO/F12 rear tires is not enough to cause any problems with the ABS/stability control. Here are all the late Ferrari wheel sizes including the 599 GTB and GTO and the F12.

If your dealer said the GTO tires may cause a handling imbalance on your GTB, that is correct. The big GTO fronts may cause oversteer, even with the one size larger GTO rears, and the stability control will intervene to try and control that oversteer.

Ferrari OEM Wheel Sizes


5 X 114.3 mm Bolt Pattern

612

Five Spoke F 18”, R 19”, 5 X 114.3 mm
Front 8J X 18 ET 43.5 mm , R 10J X 19 ET 51.1 mm
Five Spoke Modulars 19”, 5 X 114.3 mm
Front 8J X 19 ET 43.5 mm, Rear 10J X 19 ET 51.1 mm
Challenge Monolithic 20”, 5 X 114.3 mm
Front 8J X 20 ET 43.5 mm, Rear 10J X 20 ET 51.1 mm

599/HGTE/SA Aperta

Five Spoke F 19”, R 20”, 5 X 114.3 mm
Front 8J X 19 ET 43.5 mm, Rear 11J X 20 ET 63.8 mm
Challenge Monolithic 20”, 5 X 114.3 mm
Front 8J X 20 ET 43.5 mm, Rear 11J X 20 ET 63.8 mm
HGTE/SA Aperta Five Spoke 20”, 5 X 114.3 mm
Front 8.5J X 20 ET 40 mm, Rear 11J X 20 ET 63.8 mm

599 GTO

Five V/Ten Spoke 20”, 5 X 114.3 mm
Front 9.5J x 20” ET 38 mm, Rear 11.5J x 20” ET 63 mm

California/California T

Pentagram Forged, 5 Spoke 19”, 5 X 114.3 mm.
Front 8J X 19 ET 44 mm, Rear 10J X 19 ET 52.5 mm
V Spoke Forged, 5 Spoke 20”, 5 X 114.3 mm
Front 8J X 20 ET 44 mm, Rear 10J X 20 ET 52.5 mm

458

Five/Ten Spoke 20”, 5 X 114.3 mm
Front 8.5J X 20 ET 46.5mm, Rear 10.5J X 20 ET 58.5 mm

458 Speciale/Aperta

Five Spoke 20”, 5 X 114.3 mm
Front 9J X 20 ET 44.7 mm, Rear 11J X 20 ET 48.4 mm

FF

Five Spoke 20”, 5 X 114.3 mm
Front 8.5J X 20 ET 46.5, Rear 10.5J X 20 ET 53.4 mm

F12

Five/Ten Spoke 20”, 5 X 114.3 mm
Front 9.5J X 20 ET 48.4 mm, Rear 11.5J X 20 ET 71.6 mm

F12 TDF

Ten Spoke 20”, 5 X 114.3 mm
Front 10J X 20 ET 48.4 mm, Rear 11.5J X 20 ET 57.3 mm

488

Five/Ten Spoke 20”, 5 X 114.3 mm
Front 9J X 20 ET 44.7, Rear 11J X 20 ET 38.5 mm




5 X 108 mm Bolt Pattern

Testarossa

Five Spoke 16”, 5 X 108 mm
Front 8J x 16 ET 34.2 mm, Rear 10J x 16 ET 59.6 mm

512 TR/F512M

Five Spoke 18”, 5 X 108 mm
Front 8J x 18 ET 46 mm, Rear 10.5J X 18 ET 81.75 mm

348

Five Spoke 17” Early, 5 X 108 mm
Front 7.5J X 17 ET 49 mm, Rear 9J X 17 ET 68 mm
Five Spoke 17” Late, 5 X 108 mm
Front 7.5J X 17 ET 49 mm, Rear 9J X 17 ET 43.05 mm

355

Five Spoke 18”, 5 X 108 mm
Front 7.5J X 18 ET 32 mm, Rear 10J X 18 ET 77.9 mm

456 GT/456M

Five Spoke 17”, 5 X 108 mm
Front 8.5J X 17 ET 50 mm, Rear 10J X 17 ET 24.6mm

360

Five Spoke and Modular 18”, 5 X 108 mm
Front 7.5J X 18 ET 31.5 mm, Rear 10J X 18 ET 38.95 mm

360 Challenge

Challenge Monolithic 18”, 5 X 108 mm
Front 8J X 18 ET 31.5 mm, Rear 10.5J X 18 ET 39.95 mm

360 Challenge Stradale

Challenge Monolithic 19”, 5 X 108 mm
Front 7.5J X 19 ET 31.5 mm, Rear 10J X 19 ET 39 mm

550/575M/Superamerica

550/575M Five Spoke/Modular 18”, 5 X 108 mm
Front 8.5J X 18 ET 43.65 mm, Rear 10.5J X 18 ET 32 mm
575M/575 Superamerica Five Spoke Modular 19”, 5 X 108 mm
Front 8.5J X 19 ET 43.6 mm, Rear 10.5J X 19 ET 32 mm

F430

Five (Ten) Spoke, Challenge Monolithic, Scuderia Style 19”, 5 X 108 mm
Front 7.5J X 19 ET 31.5 mm, Rear 10J X 19 ET 39 mm

F430 Challenge

Challenge Monolithic, Center Lock
Front 8J X 19 H2 Center Lock, Rear 10.5J X 19 H2 Center Lock

Scuderia/16M

10 Spoke, Five Spoke 19”, 5 X 108 mm
Front 8J X 19 ET 31.5 mm, Rear 10J X 19 ET 39 mm

 

Your dealer is completely wrong if that is exactly what he said. The ABS and stability control only care about tire diameters and the relative diameters front to rear, not wheel or tire width. I would actually recommend you use F12 K2 MPSS tires in 315/35 20 on the rear instead of the GTO tires, which are K1 and have less tread depth when new. You do not need the big fronts from the GTO, 285/30 20, because they may cause too much oversteer by sticking too well up front. The GTO has different suspension settings and components than the GTB, balanced for those huge front tires. Either the 245/35 20 fronts from the GTB or the 255/35 20s from the F12 should work fine. Fabio is correct that the difference in diameter (and thus rolling circumference) between the 305/35 20 (28.41", not available in MPSS) and 315/35 20 (28.68") GTO/F12 rear tires is not enough to cause any problems with the ABS/stability control. Here are all the late Ferrari wheel sizes including the 599 GTB and GTO and the F12.

If your dealer said the GTO tires may cause a handling imbalance on your GTB, that is correct. The big GTO fronts may cause oversteer, even with the one size larger GTO rears, and the stability control will intervene to try and control that oversteer

Thank you for the feedback. One of the reasons I wanted the GTO tire at the front was so it fitted the rim properly. Up close it looks strange to have the rim sticking out from the tire, but it sounds like what your saying is the problem really arises form having the wider tire and hence more grip at the front re the traction control. I wonder if I would get away with it on standard road driving...?

 

Not me. I just help a lot of owners with wheel and tire questions. Some owners have fitted complete sets of GTO tires with reasonable results according to them, but no telling how hard they have pushed her. If you want larger tires, the F12 255/35 20s will fit the bill. Minimum wheel width for those is 8.5", so too wide for GTB wheels, but not GTO wheels.