Hi all, I used to have a rapid 1.6d on 15in alloys,car was very comfortable on our roads.

I now have a 2018 Octavia 1.5 petrol on 17in alloys and find ride very hard,I know I can run 16in alloys as on estate but only able to go from 45 to 65 profile,which is only an inch diference.

could I fit the 15in wheels from the rapid with tyres sized to keep same rolling circumference.

I don`t want to buy 16in wheels and find it still too hard a ride.

TIA, Mick.

 

Edited 21 August, 20241 yr by mickholmwood
spelling

From the snow chain section of the 07/2018 owners manual:

 

That suggest some 15" or 16" wheels might fit but it'll depend on the size of your front brakes

 

18 minutes ago, mickholmwood said:

I know I can run 16in alloys as on estate but only able to go from 45 to 65 profile,which is only an inch diference.

 

I think you have the wrong tyres sizes... The profile alone doesn't dictate the side wall height as it's a percentage of the tyre width. So a 255/45 will have a larger sidewall than a 205/45 tyre.

 

Anyway, a 'normal' Octavia (not Scout) runs:

-  6J x 16” for 205/55 R16 (~112.75mm sidewall)

-  6,5J x 16” for 205/55 R16 (~112.75mm sidewall)

-  6J x 17” for 205/50 R17 (~102.5mm sidewall)

-  7J x 17” for 225/45 R17 (~101.25mm sidewall)

 

Changing to 205/55 R16 would give roughly a 1/2 inch difference in sidewall height.

Changing to 195/65 R15 would give roughly a 1 inch difference in sidewall height (~126.75mm sidewall).

 

I assume you've checked the pressures are correct and tyre are decent quality...?

10 minutes ago, langers2k said:

From the snow chain section of the 07/2018 owners manual:

 

That suggest some 15" or 16" wheels might fit but it'll depend on the size of your front brakes

 

 

I think you have the wrong tyres sizes... The profile alone doesn't dictate the side wall height as it's a percentage of the tyre width. So a 255/45 will have a larger sidewall than a 205/45 tyre.

 

Anyway, a 'normal' Octavia (not Scout) runs:

-  6J x 16” for 205/55 R16 (~112.75mm sidewall)

-  6,5J x 16” for 205/55 R16 (~112.75mm sidewall)

-  6J x 17” for 205/50 R17 (~102.5mm sidewall)

-  7J x 17” for 225/45 R17 (~101.25mm sidewall)

 

Changing to 205/55 R16 would give roughly a 1/2 inch difference in sidewall height.

Changing to 195/65 R15 would give roughly a 1 inch difference in sidewall height (~126.75mm sidewall).

 

I assume you've checked the pressures are correct and tyre are decent quality...?

Hi, I have 225/45x17 on car, spare is 205/55x16 steel,difference in side wall height is 1in..

tyres are a quality brand. can buy 16in alloys and fit 205/55x16 tyres but not sure if it will improve ride.

want to keep same rolling circumference for speedo reading.

12 minutes ago, mickholmwood said:

Hi, I have 225/45x17 on car, spare is 205/55x16 steel,difference in side wall height is 1in..

 

How do you figure the sidewall is an inch different between those sizes...?

 

The rim is an inch different. However as you have tyre all the way round the rim, it'll only have 1/2 inch difference in sidewall height assuming the same rolling diameter (pretty close given those tyre sizes).

 

It'll probably help ride quality a little but it's impossible to give a number to help you decide.

Edited 21 August, 20241 yr by langers2k

12 minutes ago, langers2k said:

 

How do you figure the sidewall is an inch different between those sizes...?

 

The rim is an inch different. However as you have tyre all the way round the rim, it'll only have 1/2 inch difference in sidewall height assuming the same rolling diameter (pretty close given those tyre sizes).

 

It'll probably help ride quality a little but it's impossible to give a number to help you decide.

Measured from wheel rim to ground on both sizes, I am assuming both have same rolling diameter

Thats why I wondered if droping to 15in rims with tyres of same rolling diamiter would solve the ride quality

Edited 21 August, 20241 yr by mickholmwood

6 hours ago, mickholmwood said:

I used to have a rapid 1.6d on 15in alloys,car was very comfortable on our roads.

I now have a 2018 Octavia 1.5 petrol on 17in alloys and find ride very hard,I know I can run 16in alloys as on estate but only able to go from 45 to 65 profile,which is only an inch difference.

could I fit the 15in wheels from the rapid with tyres sized to keep same rolling circumference.

I don`t want to buy 16in wheels and find it still too hard a ride.

 

The Rapid rims won't fit the Octavia MK3, because the Rapid rims have a Bolt Circle Diameter of 5/100, whereas the Octavia MK3 rims have a Bolt Circle Diameter of 5/112.

 

There will be a very noticeable difference in the ride comfort for most people between 225/45R17 and 205/55R16.

 

It will help further if you go for 205/55R16 tyres with soft and flexible sidewalls, such as good quality all-season tyres. For best ride comfort avoid UHP (Ultra High Performance) summer tyres because these are made for drivers who like their cars to feel like racing cars through the corners...so have stiffer and less flexible sidewalls, which results in a harder ride.

 

Without the tyres, you might find a set of four Skoda alloys (from Skoda's accessory catalogue, not their usual parts catalogue which can be over twice the price) for about £700. Steel rims will be much less, perhaps about £240 for a set of four from an aftermarket manufacturer such as Alcar...although you would need to add a set of wheel trims for a neat appearance.

 

Here's some examples of suitable tyres and rims.

 

6.5Jx16 ET46 5/112 57.1 alloy rim 5E0071496D 8Z8

https://eshop.skoda-auto.cz/cs_CZ/alu-kolo-ilias-16-octavia-iii/p/5E0071496D+8Z8

 

6.5Jx16 ET46 5/112 57.1 alloy rim 5E0071496L 8Z8

https://eshop.skoda-auto.cz/cs_CZ/alu-kolo-new-velorum-16-octavia-iii-octavia-iv/p/5E0071496L+8Z8

 

Continental AllSeasonContact 2 205/55R16 91V (Euro label C B 70dB)

https://www.camskill.co.uk/m139b0s8003p221962/Continental_Tyres_All_Season_Car_Continental_Conti_All_Season_Contact_2_205_55_R16_91V_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_B_NoiseClass%3A_B_Noise%3A_70dB

 

Vredestein Quatrac 6 205/55R16 91V (Euro label C B 70dB)

https://www.camskill.co.uk/m139b0s8003p202105/Vredestein_Tyres_All_Season_Car_Vredestein_Quatrac_6_205_55_R16_91V_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_B_NoiseClass%3A_B_Noise%3A_70dBhttps://www.camskill.co.uk/m139b0s8003p202105/Vredestein_Tyres_All_Season_Car_Vredestein_Quatrac_6_205_55_R16_91V_TL_Fuel_Eff_%3A_C_Wet_Grip%3A_B_NoiseClass%3A_B_Noise%3A_70dB

 

In the chart below, you can see that 205/55R16 has a 0.4% smaller outside diameter compared to 225/45R17. Less than 1.5% difference is generally considered insignificant...and besides they are both Skoda approved sizes for the Octavia MK3 so this point isn't something that needs to be considered because Skoda has given both of these tyre sizes the OK.

 

Outside diameter of tyre

225/45R17 634.3mm

205/55R16 631.9mm (0.4% smaller outside diameter compared to 225/45R17)

 

Edited 21 August, 20241 yr by Carlston

4 hours ago, mickholmwood said:

Measured from wheel rim to ground on both sizes, I am assuming both have same rolling diameter

https://tiresize.com/tyre-size-calculator/

 

4 hours ago, mickholmwood said:

Thats why I wondered if droping to 15in rims with tyres of same rolling diamiter would solve the ride quality

If the spare wheel is 16" then that might be as small as you can go.

 

As put the rides comfort isn't just about the figures but also the design and build of the tyre and the materials used, two tyre of the same size (sizes are nominal btw) may give different levels of ride comfort.

 

Just as a comparison, in theory for 15" tyre size comparison (without fashion the car could easily be on 14" wheels but that's not modern styling).  195/65 r15 would be same rolling circumference as 225/45 r17 and you would get your 1" (25%) difference in sidewall height.

https://tiresize.com/tyre-size-calculator/

 

Edited 21 August, 20241 yr by nta16

Thanks for help bought a set of 16in wheels and having 205/55x16 tyres fitted today.

On 23/08/2024 at 09:55, mickholmwood said:

Thanks for help bought a set of 16in wheels and having 205/55x16 tyres fitted today.

Bought tyres online from Protyre, booked 11.00 slot at local depot.

arrived 15m early as advised,sat in waiting room till 12.00 car haden`t moved ,was told they were busy and would be 1/2 hr before starting and 1hr to fit.

Asked for refund and left.

Will go somewhere else.

On 24/08/2024 at 11:07, mickholmwood said:

Bought tyres online from Protyre, booked 11.00 slot at local depot.

arrived 15m early as advised,sat in waiting room till 12.00 car haden`t moved ,was told they were busy and would be 1/2 hr before starting and 1hr to fit.

Asked for refund and left.

Will go somewhere else.

Don't blame you

 

If they accept bookings they can't cope with,  then they are wasting customers time and deserve to get negative reviews.