285/35 vs 275/35 rears on MY08 DB9

[danieldenham]

Hi

I'm looking at options for Michelin Super Sports on the rear of my my08 DB9 with 15 spoke 19" rims. Firstly, I have been known to curb an alloy so a bit more rubber might help but also I think the rear rim/arch could do with a bit more filling. I've read a few people commenting (sub other PH threads) on the 285/35 fitments driving exactly the same as the 275 but I thought I'd start a specific tread to check.

My maths say that the increase in width gives a 3.5mm increase in diameter which I can't see affecting the speedo enough for worry.

Has anyone got any experience and comment?

Daniel



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[Speculatore]

When I change mine (2007 DB9) after Snetterton I will be going up a size all around. 275 to 285 on the back and 235 to 245 on the front. All with either Dunlop Sports Maxx or Michelin Pilot Super Sports. Getting them online from 'Tyreleader'.

[mikey k]

I used this calculator on my alloys when I upsized to my Michelin PSS's

http://www.1010tires.com/Tools/Tire-Size-Calculato...

[danieldenham]

mikey k said:

I used this calculator on my alloys when I upsized to my Michelin PSS's

http://www.1010tires.com/Tools/Tire-Size-Calculato...

Thanks, it says 1.04% too fast! which is fine.

Does anyone have any experience to say if the ride is affected? The load rating of the tyre does go from 100y on 275 to 104y on the 285 MPSSPorts. In theory, this extra load capacity may make the ride firmer but has anyone had actual experience?

Dan



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[DB9VolanteDriver]

danieldenham said:

Hi

I'm looking at options for Michelin Super Sports on the rear of my my08 DB9 with 15 spoke 19" rims. Firstly, I have been known to curb an alloy so a bit more rubber might help but also I think the rear rim/arch could do with a bit more filling. I've read a few people commenting (sub other PH threads) on the 285/35 fitments driving exactly the same as the 275 but I thought I'd start a specific tread to check.

My maths say that the increase in width gives a 3.5mm increase in diameter which I can't see affecting the speedo enough for worry.

Has anyone got any experience and comment?

Daniel


It's 7mm, not 3.5mm, increase in diameter -----> 10mm x 0.35 x 2
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[mikey k]

danieldenham said:

mikey k said:

I used this calculator on my alloys when I upsized to my Michelin PSS's

http://www.1010tires.com/Tools/Tire-Size-Calculato...

Thanks, it says 1.04% too fast! which is fine.

Does anyone have any experience to say if the ride is affected? The load rating of the tyre does go from 100y on 275 to 104y on the 285 MPSSPorts. In theory, this extra load capacity may make the ride firmer but has anyone had actual experience?

Dan



.

You are welcome they also have a good calculator for offset clearance
On the PSS I cannot recall what the load rating is but believe me they are a lot softer side walls than the OEM Bridgestones!
I found the ride improved a lot even with the pressure at 34 psi

[simonpa]

I've just done this, but went from standard Bridgestones to the 'oversize' version of Kumho Ecsta.

The ride is significantly softer, especially at the front and has eliminated the crashiness I was getting on the nearly 3 year-old half-worn Bridgestones.

Wet grip is mahoosively better - especially in severe braking, where the old front tyres would skip a lot, I haven't managed to get the fronts to go (but haven't tried an emergency stop yet).
Not had much opportunity to test cornering, but in the wet at least, the back will let go a lot more smoothly than before, especially under acceleration, where the rears would tend to tramp.

[danieldenham]

simonpa said:

I've just done this, but went from standard Bridgestones to the 'oversize' version of Kumho Ecsta.

Great info, thanks.

Anyone else with 'oversized' experience?

Dan



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[danieldenham]

Speculatore said:

..... Getting them on-line from 'Tyreleader'.

Thank you for the recommendation.

I ordered four (2x245 & 2x285) Michelin Pilot Super Sports from Tyreleader for £738 delivery!

They arrived perfectly 4 days later as predicted.

Fitting them on Wednesday.

Will feed back.

Daniel



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[Speculatore]

danieldenham said:

Speculatore said:

..... Getting them on-line from 'Tyreleader'.

Thank you for the recommendation.

I ordered four (2x245 & 2x285) Michelin Pilot Super Sports from Tyreleader for £738 delivery!

They arrived perfectly 4 days later as predicted.

Fitting them on Wednesday.

Will feed back.

Daniel

Great news. Let us know how they feel once fitted...

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