Don't think it should affect haldex much as same overall diameter on all 4, but what about ABS, ESC, and wheel well clearance? I accept the effect on speedo reading (which would probably make it more  accurate..) 

 

 

Edited 1 March, 20215 yr by AlVal

When you press reset there's a new baseline to work from so everything should work fine.

I would never run a) so much narrower tires with b) such higher sidewall on a 280, doesn't make any sense dynamically and would worsen the steering and handling noticeably in my opinion, what's even the reason to consider such a weird size combo If I may ask?

Edited 1 March, 20215 yr by newbie69

2 hours ago, newbie69 said:

I would never run a) so much narrower tires with b) such higher sidewall on a 280, doesn't make any sense dynamically and would worsen the steering and handling noticeably in my opinion, what's even the reason to consider such a weird size combo If I may ask?

Just because the rims I bought happen to have some pretty lovely almost new bridgestone potenzas on them in that size, and while my original plan was to pull them off and ebay them, I'm considering whether to just stick them on and wear them out and wait for the next change to switch over to the 225/35/20 that are the fit I'm ultimately needing.

Ultimately it is your choice what wheel/tyre you fit to your car but make your insurance company aware just in case you are involved in an accident and they may use it against you if you try and claim. My diesel offers plenty of grip from the standard Continental 235/45R18 tyres.

5 hours ago, AlVal said:

Just because the rims I bought happen to have some pretty lovely almost new bridgestone potenzas on them in that size, and while my original plan was to pull them off and ebay them, I'm considering whether to just stick them on and wear them out and wait for the next change to switch over to the 225/35/20 that are the fit I'm ultimately needing.

 

215/45R20 on 7.5Jx20 ET40 rims should give better cornering than the standard 215/55R17 size and less drag than the standard 235/45R18 size, but don't forget to use 3psi more tyre pressure than when using 215/55R17 tyres due to the lower load index of 215/45R20 tyres compared to 215/55R17 tyres.

 

Michelin Pilot 4S PS4S in size 215/45R20 95Y XL

https://www.camskill.co.uk/m63b0s9268p196556/Michelin_Tyres_Car_Michelin_Pilot_Sport_4S_PS4S_-_215_45_R20_(95Y)_XL_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_A_NoiseClass%3A_2_Noise%3A_71dB

 

If you're using BMW i8 rims, you will need 57.1mm to 66.5mm spigots to centre the rims on the hubs and probably conical wheel bolts like the BMW normally uses. Don't use the BMW i8 wheel bolts because the BMW i8 uses a M14x1.25mm thread. You will need to use wheel bolts with the Superb MK3's M14x1.5mm thread, ie. the thread's pitch is different.

 

BMW i8 2020 1.5

– Generation: Restyling [2018 .. 2022]  

– Market: USDM 

– Power: 369 hp | 275 kW | 374 PS 

– Engine: B38K15A, I3, Hybrid

– Center Bore: 66.5 mm 

– Wheel Fasteners: Lug bolts 

– Torque: 120 Nm

– Thread Size: M14 x 1.25 

– Trim Production: [2018 .. 2020]

Tire	Rim	PCD
215/45ZR20 95W	7.5Jx20 ET40	5x112	2.2
195/50ZR20 93W	7Jx20 ET36	5x112	2.2
215/45R20 95V	7.5Jx20 ET40	5x112	2.2

 

215/45R20 tyres on 7.5J rims should give you a slightly better ride than 235/45R18 tyres on 8J rims.

 

215/45R20 tyres on 7.5J rims will give you a better ride than 235/40R19 tyres on 8J rims.

 

215/45R20 tyres on 7.5J rims will give you a much better ride than 245/35R20 tyres on 8.5J rims.

 

Edited 1 March, 20215 yr by Carlston

23 minutes ago, Carlston said:

 

215/45R20 on 7.5Jx20 ET40 rims should give better cornering than the standard 215/55R17 size and less drag than the standard 235/45R18 size, but don't forget to use 3psi more tyre pressure than when using 215/55R17 tyres due to the lower load index of 215/45R20 tyres compared to 215/55R17 tyres.

 

Michelin Pilot 4S PS4S in size 215/45R20 95Y XL

https://www.camskill.co.uk/m63b0s9268p196556/Michelin_Tyres_Car_Michelin_Pilot_Sport_4S_PS4S_-_215_45_R20_(95Y)_XL_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_A_NoiseClass%3A_2_Noise%3A_71dB

 

If you're using BMW i8 rims, you will need 57.1mm to 66.5mm spigots to centre the rims on the hubs and probably conical wheel bolts like the BMW normally uses. Don't use the BMW i8 wheel bolts because that uses a M14x1.25mm thread, instead of the Superb MK3's M14x1.5mm thread.

 

BMW i8 2020 1.5

– Generation: Restyling [2018 .. 2022]  

– Market: USDM 

– Power: 369 hp | 275 kW | 374 PS 

– Engine: B38K15A, I3, Hybrid

– Center Bore: 66.5 mm 

– Wheel Fasteners: Lug bolts 

– Torque: 120 Nm

– Thread Size: M14 x 1.25 

– Trim Production: [2018 .. 2020]

Tire	Rim	PCD
215/45ZR20 95W	7.5Jx20 ET40	5x112	2.2
195/50ZR20 93W	7Jx20 ET36	5x112	2.2
215/45R20 95V	7.5Jx20 ET40	5x112	2.2

 

Thanks, I don't plan to stay with 215/45/r20, just establishing whether it's reasonably safe to use up the ones that came on the i8 rims before switching to 225/35/r20 which is a really close match to the original in terms of overall diameter. 

 

Cheers for the reminder on bolts, I forgot to check whether I'd need conical bolts

225/35R20 will give a hard ride and won't protect the rims very well from pothole damage. My preference would be 235/40R20.

 

235/40 fitted to 7.5J rims isn't an ETRTO approved combination, although some Octavia MK3 vRS owners are successfully running even lower profile 235/35 tyres on 7.5J rims.

 

Michelin Pilot Sport 4S PS4S 235/40R20 96Y XL

https://www.camskill.co.uk/m63b0s11827p167799/Michelin_Tyres_Car_Michelin_Pilot_Sport_4S_PS4S_-_235_40_R20_(96Y)_XL_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_A_NoiseClass%3A_2_Noise%3A_71dB

 

235/40R20 has a 3.8% bigger outside diameter compared to 235/40R19.

 

235/40R20 would better protect the rims from kerbing damage compared to 225/35R20, when either are fitted to 7.5J rims.

 

The load index of 225/35R20 XL (eXtra Load) tyres is only 90 (600kg) and that's not enough for the Superb MK3. 

 

Edited 1 March, 20215 yr by Carlston

1 hour ago, Carlston said:

 

215/45R20 on 7.5Jx20 ET40 rims should give better cornering than the standard 215/55R17 size...

 

Did the 280/272 ever come with that size as standard?? I wasn't aware. Judging from the 235 I run now, 215 seems awfully narrow for a car this size, this weight and this power... I'd only imagine going up in width on this car, not down.

Edited 1 March, 20215 yr by newbie69

A BMW i8 does produce a good bit of power when both the engine and motor are at full chat and is a fair bit quicker,  and much the same kerb weight as a Superb 280.

1 minute ago, e-Roottoot said:

A BMW i8 does produce a good bit of power when both the engine and motor are at full chat and is a fair bit quicker,  and much the same kerb weight as a Superb 280.

Are you sure about that? According to the car's data, curb weight is 1490kg whereas a  Superb 280 hatch starts at 1650kg in real life, that's quite some difference.

And even if they weighed similar, I doubt there's many similarities suspension/chassis wise between the two cars. The i8 was designed and set up taking into account running on these tires, the Superb didn't.

I realize the OP has a free set of that size available and is tempted to use them, I;ve been through this dilemma with an even smaller size difference than that and decided against it. 

2 hours ago, Carlston said:

 

 

235/40R20 would better protect the rims from kerbing damage compared to 225/35R20, when either are fitted to 7.5J rims.

 

Two of the rims are only 7J, so 235 would be pushing it, hence why I plan on settling on a final 225 width when I can. The rims are staggered 7 and 7.5J but the current tyres are all the same (no idea why they bothered staggering the rims...) 

 

I def want to keep same tyres on all 4 for the haldex' sake which really brings it down to  215 or 225 choice. 

 

I know the 35 profile will mean care needed around potholes and kerbs, but I'm not the type to ever kerb an alloy, and I accept the main risk for me would be not spotting a pothole in time. 

 

2 hours ago, Carlston said:

 

 

42 minutes ago, AlVal said:

 

Two of the rims are only 7J, so 235 would be pushing it, hence why I plan on settling on a final 225 width when I can. The rims are staggered 7 and 7.5J but the current tyres are all the same (no idea why they bothered staggering the rims...) 

 

I def want to keep same tyres on all 4 for the haldex' sake which really brings it down to  215 or 225 choice.

 

What offsets are the 7J and 7.5J rims?

 

This will be an ETxx number cast into the back of the alloy rims.

 

BMW i8 2018 1.5

– Generation: Restyling [2018 .. 2022]  

– Market: USDM 

– Power: 369 hp | 275 kW | 374 PS 

– Engine: B38K15A, I3, Hybrid

– Center Bore: 66.5 mm 

– Wheel Fasteners: Lug bolts 

– Torque: 120 Nm

– Thread Size: M14 x 1.25 

– Trim Production: [2018 .. 2020]

Tire	Rim	PCD
215/45ZR20 95W	7.5Jx20 ET40	5x112	2.2
195/50ZR20 93W	7Jx20 ET36	5x112	2.2
215/45R20 95V	7.5Jx20 ET40	5x112	2.2

 

https://www.wheel-size.com/size/bmw/i8/2018/

 

Edited 1 March, 20215 yr by Carlston

7J is ET36 and and. 7.5j is et40 which is close enough to perfect for the superb I reckon

1 hour ago, AlVal said:

7J is ET36 and and. 7.5j is et40 which is close enough to perfect for the superb I reckon

 

225/35 and 225/40 are not ETRTO recommended sizes on a 7J rim.

 

I would go for 215/45R20 front and 235/40R20 rear on those rims. That should also help give you more confidence and safety when cornering on the limit.

 

Outside diameter of 215/45R20 is 701.5mm

 

Outside diameter of 235/40R20 is 696mm

 

So when the front has 2.75mm of tread wear, it will equal the outside diameter of the rear tyre.

 

Or in percentage terms, the front tyre has an outside diameter 0.8% more than the rear.

 

Not only that, but there are two matching Michelin tyres in those sizes.

 

Michelin Pilot Sport 4S PS4S - 215/45R20 95Y XL

https://www.camskill.co.uk/m63b0s9268p196556/Michelin_Tyres_Car_Michelin_Pilot_Sport_4S_PS4S_-_215_45_R20_(95Y)_XL_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_A_NoiseClass%3A_2_Noise%3A_71dB

Michelin Pilot Sport 4S PS4S - 235/40R20 96Y XL

https://www.camskill.co.uk/m63b0s11827p167799/Michelin_Tyres_Car_Michelin_Pilot_Sport_4S_PS4S_-_235_40_R20_(96Y)_XL_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_A_NoiseClass%3A_2_Noise%3A_71dB

 

235/40 also isn't ETRTO approved for fitment to a 7.5J rim. However, it fits a 7.5J rim better than 245/45 fits a 7.5J rim, which is an ETRTO approved fitment.

 

The problem with ETRTO's approvals, is that ETRTO groups tyre sizes together.

 

According to ETRTO, 225/35 and 245/45 fit a 7.5J rim, but the tyre size in the middle of these two tyre sizes (235/40) doesn't fit. ETRTO has grouped 235/35 and 235/40 together, and because 235/35 doesn't fit a 7.5J rim, it follows that 235/40 doesn't fit (even though it does).

 

A second example is 185/70, 195/60, and 205/50. According to ETRTO, 185/70 fits a 4.5" rim and 205/50 fits a 5.5" rim, but 195/60 doesn't fit a 5J rim. The reason being, is that ETRTO has grouped 195/50 and 195/60 together (along with 195/55 and 195/65)...and because 195/50 doesn't fit a 5J rim, it follows that 195/60 doesn't fit a 5J rim (even though it does). In fact, the 195/60 tyre size fits a 5J rim better than a 205/50 tyre size fits a 5.5J rim.

 

A third example is 185/50, 195/60, and 205/70. According to ETRTO, 185/50 and 205/70 fit a 5J rim but 195/60 doesn't...even though 195/60 is in the middle of the other two sizes. Again, ETRTO has grouped 195/50 together with 195/60 (along with 195/55 and 195/65)...thereby preventing the approval of the 195/60 tyre size for fitment to a 5J rim. In fact, the 195/60 tyre size fits a 5J rim better than a 185/50 tyre size.

 

Edited 2 March, 20215 yr by Carlston

9 hours ago, newbie69 said:

Did the 280/272 ever come with that size as standard?? I wasn't aware. Judging from the 235 I run now, 215 seems awfully narrow for a car this size, this weight and this power... I'd only imagine going up in width on this car, not down.

 

+1.

 

@AIVal - have u considered the minimum load rating required for the Superb?

i c ur talking about circumference/diameter, rim sizes etc etc. but i don't see anything on the load rating, which is a critical factor.

58 minutes ago, JR RS said:

 

+1.

 

@AIVal - have u considered the minimum load rating required for the Superb?

i c ur talking about circumference/diameter, rim sizes etc etc. but i don't see anything on the load rating, which is a critical factor.

Without breaking it down into individual axial load, 2800kg based on Carlstons latest suggestion above (2x96 rated, 2x95 rated) , 2720kg if I run with the 4x 215/45/20 Potenzas currently on the rims (4x 95 rated), and if I stick with my original plan of 4x 225/35/20s, 2400kg (90 rated). With a full tank, driver and luggage, my car is hitting about 1800kg, so I think load rating is well within reason, even if in some alternative universe I allowed 3x fat chicks in the car. 

3 hours ago, Carlston said:

 

225/35 and 225/40 are not ETRTO recommended sizes on a 7J rim.

 

I would go for 215/45R20 front and 235/40R20 rear on those rims. That should also help give you more confidence and safety when cornering on the limit.

 

Outside diameter of 215/45R20 is 701.5mm

 

Outside diameter of 235/40R20 is 696mm

 

So when the front has 2.75mm of tread wear, it will equal the outside diameter of the rear tyre.

 

Or in percentage terms, the front tyre has an outside diameter 0.8% more than the rear.

 

Not only that, but there are two matching Michelin tyres in those sizes.

 

Michelin Pilot Sport 4S PS4S - 215/45R20 95Y XL

https://www.camskill.co.uk/m63b0s9268p196556/Michelin_Tyres_Car_Michelin_Pilot_Sport_4S_PS4S_-_215_45_R20_(95Y)_XL_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_A_NoiseClass%3A_2_Noise%3A_71dB

Michelin Pilot Sport 4S PS4S - 235/40R20 96Y XL

https://www.camskill.co.uk/m63b0s11827p167799/Michelin_Tyres_Car_Michelin_Pilot_Sport_4S_PS4S_-_235_40_R20_(96Y)_XL_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_A_NoiseClass%3A_2_Noise%3A_71dB

 

235/40 also isn't ETRTO approved for fitment to a 7.5J rim. However, it fits a 7.5J rim better than 245/45 fits a 7.5J rim, which is an ETRTO approved fitment.

 

The problem with ETRTO's approvals, is that ETRTO groups tyre sizes together.

 

According to ETRTO, 225/35 and 245/45 fit a 7.5J rim, but the tyre size in the middle of these two tyre sizes (235/40) doesn't fit. ETRTO has grouped 235/35 and 235/40 together, and because 235/35 doesn't fit a 7.5J rim, it follows that 235/40 doesn't fit (even though it does).

 

A second example is 185/70, 195/60, and 205/50. According to ETRTO, 185/70 fits a 4.5" rim and 205/50 fits a 5.5" rim, but 195/60 doesn't fit a 5J rim. The reason being, is that ETRTO has grouped 195/50 and 195/60 together (along with 195/55 and 195/65)...and because 195/50 doesn't fit a 5J rim, it follows that 195/60 doesn't fit a 5J rim (even though it does). In fact, the 195/60 tyre size fits a 5J rim better than a 205/50 tyre size fits a 5.5J rim.

 

A third example is 185/50, 195/60, and 205/70. According to ETRTO, 185/50 and 205/70 fit a 5J rim but 195/60 doesn't...even though 195/60 is in the middle of the other two sizes. Again, ETRTO has grouped 195/50 together with 195/60 (along with 195/55 and 195/65)...thereby preventing the approval of the 195/60 tyre size for fitment to a 5J rim. In fact, the 195/60 tyre size fits a 5J rim better than a 185/50 tyre size.

 

Massively good insights, thanks so much for taking the time. I'd never heard of 245 being considered on a 7.5j, I thought the notion of 235 was already extreme, but then I guess a lot of it comes down to how much sidewall you have to play with. 

 

The 0.8% difference in front /back Overall Diameter in your suggestion is pretty well within limits of haldex tolerance which I hear quoted as OK up to 3 or 4%.

 

Another beauty about your suggestion is that I can keep the 4x 215/45/20 Potenzas on the rims, taking the 2x off the back and keeping them as spares for the front, uprating the back to 235/40/20, which the Potenzas are available in.

 

But.. I _think_ Your staggered 235 and 215 suggestion doesn't give me much benefit over 225/35 all round (basing just on average tyre widths, its going to get hella technical v quickly if we start getting into contact patches, although happy to listen if you know that stuff well, I don't)

 

and if I go 225 all round, I can stay really close to the original manufacturer specced overall diameter, 0% difference front to back for haldex, and by not staggering I also feel like I'm staying closer to what's known, tried and tested. 

 

I guess it comes down to how much I want or need the protection of that extra sidewall 🤔. 

 

You know the s3 runs reverse staggered, something about reducing understeer I've heard anecdotally. I'd have to think about how staggering or reverse staggering might affect the handling characteristics on this car

 

Again, great to hear input from people who know what they're talking about 👍

59 minutes ago, AlVal said:

Without breaking it down into individual axial load, 2800kg based on Carlstons latest suggestion above (2x96 rated, 2x95 rated) , 2720kg if I run with the 4x 215/45/20 Potenzas currently on the rims (4x 95 rated), and if I stick with my original plan of 4x 225/35/20s, 2400kg (90 rated). With a full tank, driver and luggage, my car is hitting about 1800kg, so I think load rating is well within reason, even if in some alternative universe I allowed 3x fat chicks in the car. 

 

Sorry, ur not making any sense.

As long as u got it covered 

 

According to the fuel flap, the minimum load ratings r as follows:-

215/60R16 = min 95

215/55R17 = min 94

235/45R18 = min 94

235/40R19 = min 96

 

I don't know what the minimum load rating for a Superb is with 20" rims, let alone 215/45R20.

 

On the Arteon, a similar sized car to the Superb, from the VWAG family, states min 95 with 245/35R20.

 

59 minutes ago, JR RS said:

 

Sorry, ur not making any sense.

As long as u got it covered 

 

According to the fuel flap, the minimum load ratings r as follows:-

215/60R16 = min 95

215/55R17 = min 94

235/45R18 = min 94

235/40R19 = min 96

 

I don't know what the minimum load rating for a Superb is with 20" rims, let alone 215/45R20.

 

On the Arteon, a similar sized car to the Superb, from the VWAG family, states min 95 with 245/35R20.

 

 

Each tyre rated to take that much weight at its max rated speed. Of course should also consider that more of the car's weight may be over the front axle as opposed to back etc, hence my point about axial load. It's well within spec IMHO

Edited 2 March, 20215 yr by AlVal

The special-edition BMW i8 Protonic Red Edition model unveiled at the 2016 Geneva International Motor Show used 215/45R20 front and 245/40R20 rear tyres.

 

Note that 245/40R20 tyres are too wide and low profile to fit 7.5J rims.

Special edition[edit]

The special-edition BMW i8 Protonic Red Edition model was unveiled at the 2016 Geneva International Motor Show. The Protonic Red Edition will be produced at BMW Plant Leipzig from July 2016. This special edition car sports a Protonic Red paint finish with accents in Frozen Grey metallic. The colour scheme is complemented by BMW W-spoke 470 light-alloy wheels painted in Orbit Grey metallic with hubs painted in Aluminium matt and mixed-size tires (front: 215/45 R20, rear: 245/40 R20). Inside the car features red double-stitching and applications in high-grade carbon fibre and ceramic trim.

 

https://en.wikipedia.org/wiki/BMW_i8

 

PROXES SPORT

Answering the need for superior handling, new Proxes Sport was designed as a focused, sports performance tyre.

	Tire Size	Tread Depth (mm)	Overall Diameter (mm)	Overall Width (mm)	Approved Rim Width Range (inch)
	225/35 ZR20 90Y XL	7.3	666	230	7.5-8.0-9.0

 

PROXES SPORT

Answering the need for superior handling, new Proxes Sport was designed as a focused, sports performance tyre.

	Tire Size	Tread Depth (mm)	Overall Diameter (mm)	Overall Width (mm)	Approved Rim Width Range (inch)
	245/45 ZR20 103Y XL	7.7	728	243	7.5-8.0-9.0

 

As you can see above, both 225/35 and 245/45 have an approved rim width range of 7.5" to 9".

 

https://www.toyo.co.uk/

 

To keep the car legal, you need tyres that can support the maximum rated load of each axle. I would stick to at least 94 (670kg), as this is lowest load index mentioned on the fuel filler flap. It would be very easy for an insurance assessor to refuse a claim if he sees 90 (600kg) load rated tyres on a Superb MK3...and 225/35R20 really stand out as not being able to support the necessary weight.

 

Edited 2 March, 20215 yr by Carlston

Alval do I remember right you are also tuned and run closer to 360bhp?  Or was it that you were thinking of getting a remap? Or I completely confuse you with another member?