Sorry if this has been asked before but i need a new set of Michelin tyres for my 355 with oem wheels....am only interested in Michelins... Am i right in saying that the oem front size of 225/40 are fine and that the rears can be safely fitted with 295/40's instead of oem size 265/40? If so are both these sizes available as Michelin PS2's?
If you meant 295/35, that will work (295/40 is too tall). I'd stick with 265/40 though. The PS2 is outdated and very expensive if you can still find it (at least here in the U.S.). Go with the Super Sport. Comes in the OEM sizes, but not 295/35.
I went with 235/40/18 and 285/35/18 on stock rims with no problems. Many have posted that they have gone up to 295/35/18 in the rear. However, as else stated, that size is not available from many manufacturers.
I found that the stock size PS2's were narrower than the same size Bridgestones which were originally fitted to my car. I'm a huge fan of keeping things original, but ironically, a slightly wider-than-stock size PS2 is probably actually closer to the true stock dimensions. If that makes any sense.
The wheels pop out too much with the original size. I have added 10mm on both front and rear. I run 235/40 on the front and 275/40 on the back. They look more natural on the OEM wheels and in the same way a am not messing with the handling of the car.
What you want is to solve a small set (2) of mathmatical equations. 1) There is an equation for equal lateral grip front to rear:: FrontOEM/RearOEM = frontNEW/RearNEW Where front and rear are the 225 and 265 numbers respectfully. This prevents changes in oversteer/understeer. 2) There is an equations to rolling diameter (or radius): FrontOEM*FrontOEMAPR = FrontNEW*FrontNEWAPR RearOEM*RearOEMAPR = RearNEW*RearNEWAPR or if you change the wheel size: (FrontOEM*FrontOEMAPR+WheelOEM*25.4) = (FrontNEW*FrontNEWAPR+WheelNEW*25.4) Where: APR is the xxx/40 or xxx/35 number on the tire. And where: Wheel is 18" OEM or whatever NEW. 25.4 is the conversion between inches and millimetres. These equations give the same rolling radus/diamter and prevent the need to raise of lower the car. So, roughly speaking: If you go with 295/35 Rears, you are going to want: 225/265*295 = 250mm fronts, so you get a choice of 245s or 255s. Next balance the rolling diameter: 225*0.40 + 18*25.4 = 547.2 -- stock 245*0.35 + 18*25.4 = 542.9 -- 0.2" low 255*0.35 + 18*25.4 = 546.45 --the better match off by 0.75mm which is negligible.
Thanks Mitch So u reckon my 355 would handle great with these larger than OEM Michelins.... Front....255/35 Rear......295/35 Anyone else run these larger sizes?
Here is a link to a previous thread with some good discussion about tire sizes. http://www.ferrarichat.com/forum/348-355/337948-need-help-deciding-tire-size-2.html
Interesting that the wheel diameter front is smaller than rear, but that might be the way it should be...
+355 ....... the 355 OEM tire size is damn near perfect IMO ..... this is taking into account stock wheel size, engine power, contact patch, overall appearance and low un-sprung weight ....... however tire changes can be made from that OEM starting point, if you mod the car with different size/offset wheels, suspension, car height and engine/HP ......
Slight diameter difference won't be noticeable, even when pushing hard. I run 245/275 f/r and front diameter is like .5" more than stock front and rear -.2", no handling issues. Handling can be tweaked to suit using tire pressures. I settled on 37f, 33r and have very neutral handling, easily controlled with the throttle. Ran an autox today in the rain and was 5th out of 70 cars and won my class by over 5 seconds running the "wrong diameters" off by a lot more than you're talking about here.
I kept the same size front tire: 225/40/18. Went with a 295/35/18 on the rear. The Bridgestone rear size is .1 smaller than OEM. 26.2" vs 26.3". Michelin Supersports have the OEM sizes. The next size closest to OEM in the Supersports is the 285/35/18. Diameter is 25.9". It is .4" shorter than the 265/40/18.
For context, that appears to be with Challenge wheels, which are 8" wide in front and can support 245/40 tires. Probably not advisable to run that size on the 7.5" wide regular rims.
Correct, tires and wheels need to be sized similarly. Basically (above) we added 30mm to each end. One would need to add 1" (30mm/25.4 = 1.18") to each wheel for a good fitment.
Conti and other manufacturers specify a range of 8" to 9.5" for both 235/40 and 245/40. That makes your good results with the 245/40 on the 7.5" stock wheel a very useful data point.
Yep, this question has been asked many times before. That's ok though, better to see if anything has changed and get it right by asking again. That said, a lot of us have gone through this and can give you our opinions. I went from stock Bridgestones to Michelin PS2's and it was a noticeable change in handling for the better. I, along with a lot of others here, have Michelin PS2s My car: Rear - 295/35/18 w/ 15mm spacers Front - stock w/ 15mm spacers I'm not saying spacers are needed, just letting you know my fittment.
