285/35R19 to 275/30R19

[Bobby57]

I have 19" x 10" wheels currently mounted with Michelin Pilot Sport A/S 3+ tires in size 285/35R19. I wouldn't go wider than 285 on these rims. I am looking to replace the tires with the Pilot Sport 4S which has a softer compound and is generally engineered for better grip on dry pavement and better cornering.

I also have the thought to go with smaller 30 sidewalls but 30s are not available with 285 wides; I would have to go down in width to 275 to get 30 sidewalls. This would be a 21% reduction in sidewall height and a 4% reduction in tread width.

My gut tells me to go with the 275/30 as it seems that the greater stability will create an effective contact patch that will compare well with that of the wider, less stable tire?

I realize that this will make for a harsher ride.

Any thoughts?

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[deanm11]

I have 19" x 10" wheels currently mounted with Michelin Pilot Sport A/S 3+ tires in size 285/35R19. I wouldn't go wider than 285 on these rims. I am looking to replace the tires with the Pilot Sport 4S which has a softer compound and is generally engineered for better grip on dry pavement and better cornering.

I also have the thought to go with smaller 30 sidewalls but 30s are not available with 285 wides; I would have to go down in width to 275 to get 30 sidewalls. This would be a 21% reduction in sidewall height and a 4% reduction in tread width.

My gut tells me to go with the 275/30 as it seems that the greater stability will create an effective contact patch that will compare well with that of the wider, less stable tire?

I realize that this will make for a harsher ride.

Any thoughts?

275-30-19 is a 25.5" tire. While you have a bit more sidewall staying close to stock ~27" diameter, you get a bigger contact patch with a taller tire. I wouldn't go that small of a diameter.

 

[Bobby57]

275-30-19 is a 25.5" tire. While you have a bit more sidewall staying close to stock ~27" diameter, you get a bigger contact patch with a taller tire. I wouldn't go that small of a diameter.

The reduction in width would be 10mm (4%). There is some literature that says the the stiffer side wall would better maintain contact patch in turns?

 

[deanm11]

Well, yes all else equal less sidewall generally leads to better handling, but due to less squirm in the sidewall. A 20" wheel could give you a similar sidewall for that handling benefit and also give the larger contact patch of the more stock size diameter tire. For straight-line, particularly off-the-line traction you want some sidewall. I'm going to run 305-40-18s in the rear on my new setup. As a comparison this gives me a 4.8" sidewall while your hypoethetical 275-30-19s are 3.25". Finally, in my personal estimation, the handling limits, at least anything on the street, are so high that I personally want more sidewall for the straight line traction and also ride comfort. Without as much give, small sidewalls will ride harder.

 

[NightmareMoon]

The 30 sidewall will not really improve any aspect of handling. Sure it won't squirm around, but it also won't be able to absorb imperfections and bumps as easily. It would also look kinda silly small in the wheel wells.

Best to stick to 35 or 40 with a 275 MP4S. I'd personally (and have) 285/35R19 MP4S, cause that's even better.

 

[Bobby57]

Well, yes all else equal less sidewall generally leads to better handling, but due to less squirm in the sidewall. A 20" wheel could give you a similar sidewall for that handling benefit and also give the larger contact patch of the more stock size diameter tire. For straight-line, particularly off-the-line traction you want some sidewall. I'm going to run 305-40-18s in the rear on my new setup. As a comparison this gives me a 4.8" sidewall while your hypoethetical 275-30-19s are 3.25". Finally, in my personal estimation, the handling limits, at least anything on the street, are so high that I personally want more sidewall for the straight line traction and also ride comfort. Without as much give, small sidewalls will ride harder.

I hear you about the benefits of the higher sidewall.....it is part of my decision struggle. As to 20" wheels, too much unsprung weight in my estimation...unless one forks over for forged

 

[deanm11]

My 305-40-18 rear drag radial and 245-45-18 front summer tires on Enkei 18s is 35lbs lighter than the stock 18" setup!! So I am all about unsprung weight reduction. I had a smaller 17" in rear setup that was 50lbs lighter (for sale) but requires a bit of brake 'clearancing'

 

[Bobby57]

My 305-40-18 rear drag radial and 245-45-18 front summer tires on Enkei 18s is 35lbs lighter than the stock 18" setup!! So I am all about unsprung weight reduction. I had a smaller 17" in rear setup that was 50lbs lighter (for sale) but requires a bit of brake 'clearancing'

Ah, racing wheels...forged? .....quite a weight savings.

I replaced stock 19" x 9" with 19" x 10" and saved 8 LB per wheel and thought I was doing well :-)

 

[deanm11]

These, the RPF1s. Made in Japan too.

https://enkei.com/shop/wheels/racing/rpf1/

 

[Bobby57]

These, the RPF1s. Made in Japan too.

https://enkei.com/shop/wheels/racing/rpf1/

They use a MAT process which seems to be what some manufacturers are calling "flow formed" --- squeezing the aluminum into a uniform, linear grain pattern. My Apex wheels are made with this process....a good compromise between cast and forged.

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