What size tires are best to fit 19" wheels on a 456

For my 456M I run 255/35-19 on the front and 295/30-19 on the back. No issues whatsover. You can also go much wider on the as some run 355 like on the Maranellos (per Taz in another thread).

I will upgrade to 355/25 when these run through- great look.

 

Michael- The size of tire is really dictated by how wide your rear wheels are. If you have a rear wheel 10-11" wide, the OEM 19" tire size of 305/30 19 is used on the 575M and Superamerica and would work fine.

For the very wide 12.5J X 19 Novitecs or the wheels you bought, the 305/30 19s are too narrow, and you need 355/25 19s or a near size. TireRack has a list of Pirelli P Zero Rossos showing recommended wheel widths for each size. The 255/35/19s Tajaro mentions should work fine on 9.5" front wheels.

Taz
Terry Phillips

 

Michael- Here is how to crunch the numbers on tire diameter. Math is pretty simple.

550/575 OEM 18" R 295/35 18

(295 mm X 0.35 X 2 (top and bottom)) = 206.5 mm ÷ 25.4 (mm/in) = 8.13" + 18" = 26.13"

550/575 OEM 19" R 305/30 19

(305 X 0.30 X 2) ÷ 25.4 = 7.20" + 19" = 26.20"

355/25 19

(355 X 0.25 X 2) ÷ 25.4 = 6.99 " + 19 " = 25.99"

Close enough. 0.54% difference between the 295/35 18 and 355/25 19.

365/25 19 would be closer, but nobody makes one.

Taz
Terry Phillips

 

Michael- The rears should be fine, but I would be worried about the fronts being too wide and causing interference when the steering is turned hard-over.

Here is the list of recommended rim widths for each tire size. 255/35 19 should work fine on your 9.5" front rims.

http://www.tirerack.com/tires/Spec.jsp?make=Pirelli&model=PZero+Rosso&tirePageLocQty=

Taz
Terry Phillips

 

I really don't think we can put 295 on the front - I'd be shocked if they wouldn't rub. And it's odd the 345 in 20 inch rim says 11-13.5 inch rim while the 355 wants 12.5-13.5. You think that's a typo?

 

TJ- Entirely possible. Always have to look at the big picture and apply judgement on this kind of data.

Taz
Terry Phillips

 

If you have Novitecs the only wheel package that will work properly without rubbing is what Taz suggested - 255/35/19 upfront. and 355/25/19. I am speaking from experience as the 355 were back-ordered for almost a year when I got my set so I had to try different permutations. You can't fit a 315 on the 12.5 rim, I put 345/30/19 (Viper tires - only other "close fit") and the different diameter with the fronts causes ABS to go crazy, so you have to go with a taller tire in the front to correct that - and then the tires will rub. Anything wider then the 255 will be problematic.

Avoid the headaches, go with recommended sizes and use 25mm spacers in the back (not the 30mm which causes the wheels to stick out too much)
Franck

 

Frenchie- Thanks for the real-life input on 456 sizes. An adjunct to that is the ABS system can apparently only handle about 4-5% difference in sizes front to rear. More than that and you end up with an ABS light and no ABS capability. Usually more of a problem with the mid-engined cars than our front-engined V12s, but worth noting.

I really wish Michelin would come out with sizes for their PS2 Zero Pressures for our cars. Same tire fitted to the ZR1. Stick like glue, last 20K miles or so, and no worries about getting a flat. Pretty much only Corvette sizes so far, but more are being added.

I put 25 mm spacers on the back of my 575M in hopes I could eventually afford Novitecs. Plus they look better with stock 550/575M 18 and 19" wheels.

Taz
Terry Phillips

 

Michael- 27.14"-26.02" = 1.12" ÷ 26.02" = 4.3% difference, which is approaching, or may exceed, the ABS limit. I would also worry about those rear tires being 1" larger than stock and rubbing, but no way to tell without doing a fit check. Franck (Jagbuff) says that combination will give you problems with the ABS from personal experience. Read his post again. Apparently the rears fit ok, but......

Also remember he has Novitec NF2s with rear offset of 51 mm, what offset are your new rear wheels? Will make a difference

Taz
Terry phillips

 

Hi boys, has any of you used non factory spec tire sizes for your stock 17" on the 456?

I can't find the 255 & 285 over here and the only set I managed to find is 4yrs old but unmounted for the rears.

I was told that 275, 40 & 17R is a lot easier to get for the rears.

 

Franck is correct about the 30mm spacers being too big. The wheels will stick out beyond the wheel arch. I used 15mm spacers from Hills and find them just right. Even 20mm were just a bit too close to the edge of the arches but 15mm brings them just inside and look the nuts!

 

Use a calculator.

http://www.1010tires.com/tiresizecalculator.asp

 

Dave- I can do tire calculations just about as fast on a calculator. Plus when you are done, you actually understand what you did. Guess I was an instructor in the AF too long.

Taz
Terry Phillips