Tyre sizes

[huesey1974]

Hi,
Apologies about another tyre threab but my search didn’t turn up what i was looking for, however if i missed it im sorry in advance. I have owned my 2011 GRANTURISMO for 1 week now and i love it, i decided to have my 20” trident alloys fully refurbished as they had a few scuffs and some light bubbling. I got the car back today and they look perfect. However they have 4 year old pzero tyres, i think they are noisy and also feel skittish, they have around 5.5mm of tread. I had them on one of my previous Mercs and didn’t like them back then either. So im thinking about binning them, can i go 295/35/20 rear and 255/35/20 front? I can get rear MPS4S rears for £150 which seems a real good deal. Also thinking Vredestein Vorti, had Vreds before and thought they were very good although not Vorti. Any info much appreciated.
Thanks

 

[Gazcw]

295 30 20 rears with 35 fronts, MPS4S all round have transformed my qp. Gone from jittery to planted.

 

[JimT]

I put Bridgestone on mine.
Find them really good. Car feels planted.
They are the recommended size though on 20" wheels

 

[Zep]

Those are the standard size for the Stradale, so they should fit, the rolling circumference is slightly different, so it will have a small effect on the speedo reading.

 

[JimT]

So we're saying 295 35 20 rear and 255 35 30 front ok for the standard granturismo?

 

[Zep]

So we're saying 295 35 20 rear and 255 35 30 front ok for the standard granturismo?

I’m not your insurance broker, but they will fit.

 

[huesey1974]

I put them on with zero issues, with the spacers they look great. I went for the Vred vorti. Feels much better and much less noise than the pzero.

 

[Gazcw]

It should be 30 on rear and 35 on front due to the staggered sizes shouldn't it?

 

[Gazcw]

So we're saying 295 35 20 rear and 255 35 30 front ok for the standard granturismo?

If you match the profiles you have a large outer diameter difference and I would not drive it at high speed. Other nutters might!
295/35 = OD 715mm
255/35 = OD 687mm
295/30 = OD 685mm

So a 295/35 and a 295/30 has near identical diameters

 

[Gazcw]

https://www.tyresizecalculator.com/charts/tire-size-chart-metric-by-rim-wheel-diameter

Or looking at it another way. The rear of a 35 profile will do 29.3 revolutions per mile less than the fronts. A rear with 30 profile will do 2 less. I think you would feel that difference.

 

[Zep]

If you match the profiles you have a large outer diameter difference and I would not drive it at high speed. Other nutters might!
295/35 = OD 715mm
255/35 = OD 687mm
295/30 = OD 685mm

So a 295/35 and a 295/30 has near identical diameters

The cars have a that difference in diameter as standard. It seems to drive pretty well from my perspective.

 

[Gazcw]

The cars have a that difference in diameter as standard. It seems to drive pretty well from my perspective.

Interesting. Here is mine. I run 245/35 and 295/30

 

[huesey1974]

https://www.tyresizecalculator.com/charts/tire-size-chart-metric-by-rim-wheel-diameter

Or looking at it another way. The rear of a 35 profile will do 29.3 revolutions per mile less than the fronts. A rear with 30 profile will do 2 less. I think you would feel that difference.

Minimal difference.
Standard 245/35/20 , 285/35/20 rears do 19 revs per km less
wider 255/35/20, 295/35/20 rears do 18 revs less

 

[Gazcw]

Its not the width but the profile. Having matching profiles results in the rears doing less revolutions than fronts but as Zep says, his are the same as per manual. All very strange and confusing!

 

[huesey1974]

Its not the width but the profile. Having matching profiles results in the rears doing less revolutions than fronts but as Zep says, his ard the same as per manual. All very strange and confusing!

Sure is, I spent plenty of time going over plenty of threads before committing, defo no issues, even seen some guys over the pond with some bigger ones on again. Don't look right though.

 

[eight]

I’m looking at tyres and found this thread. Current front Pirelli’s are worn on inner edges, favourite seems to be Michelin’s. I’ll do all four to keep a matching set. It deserves it!
Reason for posting - I had a CLS55 with 10mm oversized Pirelli’s on the back fitted by previous owner (oversized as per US forum advice) and always thought it was the car that felt so unplanted at the rear, squirmy on full throttle etc. Up on the ramp under the car my tyre and mot guy pointed out how far over the inner rims the rear tyres were - inner sidewalls were sloping literally at 45 degrees. Might just have been a pirelli thing as the outer sidewalls looked ‘right’ but honestly the inner walls looked ridiculous. Changed to the pricier smaller correct sized Goodyear’s and it was like night and day, car felt locked to the tarmac on the factory sized rubber.
Just sayin’!

 

[Gazcw]

I’m looking at tyres and found this thread. Current front Pirelli’s are worn on inner edges, favourite seems to be Michelin’s. I’ll do all four to keep a matching set. It deserves it!
Reason for posting - I had a CLS55 with 10mm oversized Pirelli’s on the back fitted by previous owner (oversized as per US forum advice) and always thought it was the car that felt so unplanted at the rear, squirmy on full throttle etc. Up on the ramp under the car my tyre and mot guy pointed out how far over the inner rims the rear tyres were - inner sidewalls were sloping literally at 45 degrees. Might just have been a pirelli thing as the outer sidewalls looked ‘right’ but honestly the inner walls looked ridiculous. Changed to the pricier smaller correct sized Goodyear’s and it was like night and day, car felt locked to the tarmac on the factory sized rubber.
Just sayin’!

It will be night and day switching from Pirelli anyway I would think.

 

[huesey1974]

Hi,
No issues with the wider tyres, don't look anything but normal, the tyres are the max size for the rims. anything bigger may look bad. Very impressed with the Vred's also.

 

[rs48635]

all very confusing when 20" wheels of same sizes have marginally different tyre for QP compared to GT
Will be checking mine again in daylight. Sure I put 295 on the rears, well nearly sure.....