255/40/18 tires on late 2019 RS 3 build?

[Rod Paine]

I am getting all kinds of OPINIONS as to what is the actual capability of using a 255/40/18 Michelin AS4 on our late build 2019 RS 3, without getting into tire contact problems in the front wheel well. Am currently running 245/40/18 Michelin AS3+ on Neuspeed RSe10 wheels but the country back roads we run in W VA and VA have some bad road surface areas and I really need a tire with more sidewall height. Anybody here who can CONFIRM if the 255/40/18 is a possible fitment based on actual use?

We run these roads an average of 3 days a week, 80-110 miles per run weather permitting and now with 12k miles on the 245/40/18 Michelin AS3+ tires they need to be replaced. But I want to involve taller sidewalls to deal with this issue.

3" sidewalls on the stock 235/35/19 tires were killed within 3k miles. The 3.9" sidewalls on the current 245/40/18 wheels have survived thus far but they've been 'hurt' . Thus our desire to involve tires with a 4-inch sidewall to better deal with these road defects. Been running these roads 30+ years and certainly prefer to continue their use due to my lengthy experience on them.

Had these roads been PROPERLY maintained this would of course not be a problem now, which they are! Sign of the times with our roads in the U.S. versus 10-15 years ago!

[Dominick's S4]

Not exactly what you are looking for but very close. I have not had any issues with this set up.

Tires - 255/35/18 Michelin MP4S
Wheels- Neuspeed RSe10 - 18 X 9.0, 5x112. Weight: 19.75lbs. Offset: +45mm, Satin Black Center Bore: 66.56mm / 57.1mm (with metal hub ring)

[S3DUDE]

Hi Mr Paine,


I am running 255/ 35/18 on RSE10 but I will consider 255/40/18 next time. Tucson roads got a little better since you were here Drag racing 63 year ago at the Air Force base, we no longer have F-86 Sabres nor B-47 bombers neither the Titan 2 ICBMs but Mount lemon road is a whole lot better. Greetings from sunny Arizona and God bless you and give you many more years healthy driving behind the wheel.

[Rod Paine]

S3DUDE,
Good to hear from you again! Ya lots of aircraft no longer at Davis-Monthan, especially my favorite the B-29's which there were about 600 of at that time I and my school friends played in for several summers in the mid 1950's. How is the Sabino Canyon road now days? We used to stage a lot of night drag races there.

Yes I looked at the 255/35/18 but didn't want to go to the lower sidewall height, given the road conditions and the fact that our
245/40/18 with its slightly taller sidewall is still taking a beating thus a taller 255/40/18 configuration as a possible REAL solution.

But no body has reported actually running a 255/40/18 on a 2019 RS 3. Several have commented it will not fit at all while others say 'no problem'. So still looking for actual user experience with the 255/40/18 running a Michelin AS3+ or AS4... before I have to go to the trouble of buying one and doing a test fitting.

[Paul@SupremePower]

255/40-18 is too large. Below is the result with lowering over 8.5 +44:




Doing same on 9 +45 would same issue if not worse due to the more outboard position.

[Rod Paine]

Is this on a late build 2019 RS 3, ot an earlier version? The wheel looks like it has a hub adapter of some sort on the face of the caliper? What is the brand of the mounted tire?

[Paul@SupremePower]

Is this on a late build 2019 RS 3, ot an earlier version? The wheel looks like it has a hub adapter of some sort on the face of the caliper? What is the brand of the mounted tire?

Not sure of year but wheel fitment is same. Wheel is Titan7 18x8.5 +44 with a ring to 57.1. Tires are PS4S

[NoggieRS5]

255/40-18 is too large. Below is the result with lowering over 8.5 +44:




Doing same on 9 +45 would same issue if not worse due to the more outboard position.

Hey Paul, would it be the same problem if you're not lowered? My car has the RS Fixed Suspension. I just want to make sure that a 40 profile on a 255 width won't fit.
I think it would be good to mention the max profile on your wheel fitment posts cause that's what I've been referring to each time I feel in the mood to look at wheels and tires.

[Rod Paine]

Hey Paul, would it be the same problem if you're not lowered? My car has the RS Fixed Suspension. I just want to make sure that a 40 profile on a 255 width won't fit.
I think it would be good to mention the max profile on your wheel fitment posts cause that's what I've been referring to each time I feel in the mood to look at wheels and tires.

GOOD QUESTION! I've had one person email me saying it is not an issue on the late 2019 build RS 3 FIXED SUSPENSION such as I also have. Still would like to run 255/40/18 as our country back roads aren't getting any better! And while our Michelin AS3+ 245/40/18 on Neuspeed RSe10 18x8.5 wheels seem able to deal with our road conditions, they are now showing obvious significant wear at 8,000 miles of these roads use, versus our total 12,450 miles on the RS 3.

The problem is simply being able to deal with poor road conditions that have pot holes, badily worn areas with heavy grooves and breaks and other surface problems that very low profile tires (235/35/19 for example) don't survive very long subjected to such surfaces at speed, as we've experienced.

[brobst]

Want to bring this back and ask, for those running 18s, what air pressure are you doing all around?

[JOBJOB]

36 or 37 I think on 225/45/18.
Check https://tiresize.com/pressure-calculator/

[Dominick's S4]

Want to bring this back and ask, for those running 18s, what air pressure are you doing all around?

Daily I run 38psi on the fronts and 36psi rears with a square setup. At the track I add a few pounds all around and at the drag strip I go 27 front and 29 rear..

[Rod Paine]

Still running 40 psi front and 38 psi rear. Made a few test runs last week during much colder days and no changes made.
These are with 245/40/18 Michelin A/S3+ at 15,939 miles on the tires. 71% fast country back roads, remaining 29% normal occasional drives to town. Approaching replacement soon as tread depth is near minium depth.
FWIW

[Spinnetti]

Weird. Tire differences maybe? I'm on 034 springs on my S3 with 255/40-18 on 18x9 ET30 - running several brands of tires with loads of room, even fully loaded with 4 adults. YMMV I guess but if anything the RS3 should have more room rather than less unless dumped on coilovers silly low?

[DarbyWalters57]

RSe10 19x8.5 265/30/19 Front (5mm Spacer)
RSe10 19x8.0 255/30/19 Rear (5mm Spacer)

Michelin Pilot Sport Cup 2 Connect (240)
https://www.tirerack.com/tires/tires...C2XL&tab=Sizes

[Phayl]

Weird. Tire differences maybe? I'm on 034 springs on my S3 with 255/40-18 on 18x9 ET30 - running several brands of tires with loads of room, even fully loaded with 4 adults. YMMV I guess but if anything the RS3 should have more room rather than less unless dumped on coilovers silly low?

Nope, 255/40r18 does not fit on a normal to oversize tire. Narrow tires it may. Even with an OE offset, so shorter sweep than aggressive offset it'll still rub as Paul shared above. I ran 18x8.5 +27 on my RS3, which is less aggressive than your x9 +30 and rubbed on full lock with a 245/40r18 PS4S. You using ling long tires?

Honestly think it's down to caster between 4 pot 8v and 5 pot 8v, or possibly subframe positioning.. I run 265/35r18 (will replace with 285/35r18) tight tires on 18x9+32 and 18x937 for track with 0 issue @ -2.7 front, -1.8 rear.