488 255/315 on stock wheels

Hey guys - time for new tires. 2017 488 GTB stock wheels

Currently running : Pilot Sport 4S 245/35/20 & 305/30/20 rear

Thinking about going to: Pilot Sport 4S 255/35/20 & 315/30/20 rear

Simple math tells me the overall diameter is about a 0.25" taller but the differential from front to rear is about the same at ~0.4", which is what I understand the F1-Trac etc is sensitive to.

However I do know not all tires measure out to their specs!

Has anyone run these sizes on the OEM wheels?

Any issues with traction control?

Rubbing on stock suspension / offsets?

Thanks

 

The diameter shouldn’t change at all with what you wrote… you only went wider.


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Why?

 

I put 255s on the front of mine and didn’t like the larger look so went back to 245s. The side walls on a 9 inch rim go almost straight up and down and do not roll inward. So the tires appear much larger than just the diameter change. The 245s had a better looking ratio to my rears. Although I have 20/21 setup but have 315’s in the rear and imho it does a great job filling in the fender gap. Keep in mind offsets make a huge difference in the appearance along with wheel width.

A great website for calculating Tire diameters and comparisons is….
https://tiresize.com/comparison/

In the end, I think it comes more down to personal preference than anything. Sometimes you have to search hundreds of photos to find somebody with a the similar set up

It was helpful to see other peoples cars on this forum before I purchased my Wheels & Tires.

 

Thanks guys. while i know the diameters should be correct, ive always experienced variation between manufacturers and even within the same manufacturer so am looking for some first hand experience

I dont feel like i get all the power down at wide open throttle, very traction limited. I'm hoping a little more width out back will help hook up a little better. so not for cosmetic purposes just trying to get more traction, but dont want the diameters to screw up the traction control and have it start cutting power

 

The side height of the tire is a function of the width - so with the same profile (e.g. 30 or 35), the height increases with the width, leading to a larger diameter.

 

This is part of an old post, I only kept a screenshot, I cannot agree more. 315 is not an option.

Stop stop stop! Don't order anything! Forget the width and all the rest of it. It is a 100% no-go. Many tried it when the Speciale was released. The ESC and ABS system does not work with that much of a difference compared to OE front to rear diameter bias. OE rears are 6% larger in diameter than the fronts. What you're trying to do, is get away with 2.7%.
It's a big no.
Smallest diameter that will work, is 325/30R20. However, the much wider rears will make the car push like mad and understeer into next week.
Exactly what is your goal? Do you track? Cruise the back roads?
If you track, I'd suggest getting a set of Speciale wheels and fit them with MPSC2 rubber in 265/30R20 front and 325/30R20 rear. A few dedicated track rats ran that setup in my neck of the woods some years back, and it was a well balanced setup which was much less prone to understeer than stock.
If you're mostly, or always on the road but you're looking for a bit more width for both looks and bite, MPS4S in 245/35R20 and 305/35R20 is a viable option. This size will fill the large wheel wells nicely, and they will fit the OE wheels.
Your OE rims can in fact accommodate the F12 set of MPSS should you so desire.
But again. No to the 305/30 and 315/30.
^

 

I would stay stock sizes on 20's. You will gain nothing really with the sizes you listed and possibly run into odd behavior with ABS and traction control due to the car sensing wheel speed differences.

I run HRE stock 20" wheels just a touch better offset and stock K2 Michelin Sport Cup 2. They offer a bit better grip in a hot summer than the OEM Pirelli P Zero. Cup2 is not great in the rain but I do not go out in my 488 if it is raining anyway. I have 6k miles on my Cup2 and they are wearing very well. They are more street than track tire but have multiple compound so the tire is softer towards the outside of it. Better grip in the corners when hot. I ran this tire a lot on my Porsche GT3's at Sebring, Daytona, Barber and Homestead so I know the tire very well. Summer days in Florida helps getting tire temp up for ore grip but the 488 can still break them lose.

Here is a pic of one of my rears. Here is the car on stock size 20's.
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your car is sitting real nice. can you share your rims OFFSET and tire size ?

 

20x11 et21
20x9 et35

I no longer have my 488 and I sold the HRE wheels. Now have a F8 and have not altered it.
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nice F8 mate. also your old 488 seem to be lowered right with the HRE wheel ?

 

Yes 488 was on Novitec springs