Carlston

Fitting heavy oversize 16" wheels that increase the unsprung weight and raise the centre of gravity won't help the handling. 16" tyres are also expensive, so if you try and economise by buying cheap 16" tyres that won't help the handling either. On an old Fabia, you might be better off fitting new good quality shock absorbers. The original Mazda MX5 used 185/60R14 tyres and for good reason. Skoda Fabia ATIC Alloy Rim 6Jx14 ET37 http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/FAB/year/2008/drive_standart/608/hg_ug/601/subcategory/601040/part_id/2543668/lang/e Steel Rim 6Jx14 ET37 http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/FAB/year/2008/drive_standart/608/hg_ug/601/subcategory/601010/part_id/2543667/lang/e Michelin CrossClimate 185/60R14 86H XL https://www.blackcircles.com/catalogue/michelin/crossclimate/185/60/R14/H/86/m?tyre=35184256 Fitting 185/60 tyres to 6J rims will give sportier handling than fitting them to 5.5J rims, at the expense of comfort.

5Jx14 ET35 rims with 185/65R14 tyres is a good choice for comfort. Even going to 15" rims would reduce the ride comfort unless you fit oversize tyres such as 185/65R15 or 195/60R15. 195/55R15 might be a good compromise and at least keeps the gearing close to standard. If you want bigger wheels, it's best to get a bigger car such as the Octavia. That will take 16" wheels without spoiling the ride as the outside diameter of the tyres is over 1" bigger.

Just to add to the 225/45R19 suggestion...the Kodiaq has a 7Jx19 ET43 rim option. These look similar to the VEGA 8Jx19 ET45 rims from the Karoq. See the two links below for photos of the 19" CRATER rims from the Kodiaq. CRATER 7Jx19 ET43 Rims from the Kodiaq in Matte Black https://eshop.skoda-auto.cz/cs_CZ/kolo-z-lehke-slitiny-crater-19-pro-kodiaq/p/565071499++ZG6 CRATER 7Jx19 ET43 Rims from the Kodiaq in Anthracite https://eshop.skoda-auto.cz/cs_CZ/kolo-z-lehke-slitiny-crater-19-pro-kodiaq/p/565071499++ZG6 225/45R19 tyres fitted to 7J rims will ride a lot softer than when fitted to 8J rims.

According to ETRTO, 255/40 is too big for an 8J rim. 245/40R19 might be a good choice. 245/40R19 has the same load index as 215/55R17. 215/55R17 is a standard size on the Karoq. The outside diameter of 245/40R19 is almost identical to 225/55R17. 225/55R17 is a standard size on the 4x4 Karoq. Outside diameters 215/55R17 668.3mm 235/40R19 670.6mm 245/40R19 678.6mm 225/55R17 679.3mm 225/45R19 685.1mm 255/40R19 686.6mm 235/45R19 694.1mm The Kodiaq uses 235/45R20 on 8J rims, so 235/45R19 on 8J rims could be an option for the Karoq. 235/45R19 is 1.3% bigger than 225/45R19.

I use warm soapy water and a 1" paintbrush and an old toothbrush to clean the wheelarch and any exposed threads the day before. You don't want to be trying to fit too much into one day, especially if you don't know what you are doing. Getting rid of as much dirt before getting down to serious work helps enormously.

What size tyres have you got fitted? 225/40R19 or 225/45R19 ? If you have 225/40R19 tyres, then fitting 225/45R19 tyres will improve the ride...especially if you lower the tyre pressures by 3psi (0.2Bar). The reason that you can lower the tyre pressures by 3psi when changing from 225/40R19 to 225/45R19 is because the higher sidewalled tyre can support the same amount of weight using 3psi less tyre pressure. This is reflected in the different load indexes of these two tyre sizes. 225/40R19 has a load index of 89 (580kg) @ 44psi, whereas 225/45R19 has a load index of 92 (630kg) @ 44psi. For example, 580/630x35psi=32psi. To do the maths, you form a multiplier by taking the load index of the original tyre and divide it by the load index of the replacement tyre. You then use this multiplier to multiple the original tyre pressure...which gives you your new reduced (and more comfortable) tyre pressure. The 4x2 Karoq when fitted with 19" wheels has 225/40R19 tyres, whereas the 4x4 Karoq when fitted with 19" wheels has 225/45R19 tyres. The standard tyre options on new Karoqs in the UK are either 17" or 19". https://cc.skoda-auto.com/gbr/en-GB/trimline-scenic?_ga=2.210707863.348432214.1608996413-0a2cf681-cbb9-4a54-988d-1bb2bc4df8a8&activePage=trimlines&color=K4K4&configurationId=&extraEquipments=&id=GBR%3Bskoda%3B2021%3BNU73B5%3B0%3BGYO2YO2%3Bmda20200804034704%3Ben-GB%3B%3B62001%3B62061&interior=AD&modifiedPages=&snapshotVersion=e0456e00-f767-4c80-854f-216feb5b3ce1&trimline=NU3|SE6206162001&visitedPages= 19" Crater Rims 8Jx19 ET45 https://eshop.skoda-auto.cz/cs_CZ/kolo-z-lehke-slitiny-crater-19-pro-karoq/p/57A071499++HA7 Even with a change from 225/40R19 to 225/45R19, the 19" rims on the Karoq are 8J. This is the width of the rims, ie. 8". This is wide for a 225/40 or 225/45 tyre and stretches the tyres' sidewalls which makes the ride harder. As a comparison, the Skoda Octavia will often use a much narrower 7J rim when fitting 225/45 tyres albeit in 17" format. Even with the 225/40 size, the Octavia still uses narrower 7.5J rims.

My preference would be for Sealey over Hilka. You get good customer support from Sealey, and they do a nice line of trolley jacks. However, the Hilka one that you linked to on Screwfix, looks exactly the same design...probably made in the same factory in China. https://www.ebay.co.uk/itm/SEALEY-2-PCE-CAR-COIL-SPRING-COMPRESSOR-KIT/191412238567?epid=1840770360&hash=item2c910ef8e7:g:114AAOSwGAhfs6su Sealey AK3841 (Short version) https://www.sealey.co.uk/product/5637175238/2pc-coil-spring-compressor Sealey AK3846 (Long version) https://www.sealey.co.uk/product/5637175243/2pc-long-reach-coil-spring-compressor

Amazon were selling the Draper14173 coil spring compressors for under £20 earlier this year. They seem to be overpriced at the moment. It might be worth looking at a better value option. Your original Hilka ones might have an Acme thread after all. I was thinking about some even cheaper ones that I purchased for £7.99 that went straight in the bin. Rubbish compressors that went straight in the bin (not from this seller...but same design) https://www.ebay.co.uk/itm/2x-Heavy-Duty-Coil-Spring-Compressor-Clamps-Suspension-Shock-Absorber-Struts-NEW/274128603435?epid=1454404298&hash=item3fd356892b%3Ag%3ARIUAAOSw-TFd6PXP&LH_ItemCondition=1000

Snow chains The snow chains improve driving in wintry road conditions. Before fitting the snow chains, remove the full wheel trims. Snow chains must only be fitted on the front wheels and are applicable only to the following tyre/rim combinations. Octavia MK3 Scout (a) 205/55R16 6Jx16 ET48 (a) 205/55R16 6Jx16 ET50 (b) 205/60R16 6Jx16 ET48 (a) 205/50R17 6Jx17 ET45 (a) 205/50R17 6Jx17 ET48 (b) 205/55R17 6Jx17 ET48 Notes: (a) Only fit snow chains with links and locks no larger than 12 mm (b) Only fit snow chains with links and locks no larger than 9 mm. The above information about tyre and rim combinations for snow chains is in the owner's manual on page 282. https://ws.skoda-auto.com/OwnersManualService/Data/en/Octavia_5E/07-2019/Manual/Octavia/A7_Octavia_OwnersManual.pdf?_ga=2.107158530.1213152461.1608930222-dfe66703-8989-42cc-99fc-86d69f1fa428

The threads are not Acme threads, but ordinary bolt threads. These literally destroy themselves with very little use. You really need an Acme thread for a spring compressor. This is the same type of thread that they use on bench vices, so very strong and long lasting. I've got these two coil spring compressors. The more expensive one, has plastic cups which stops the paint on the coil springs being chipped off. https://www.machinemart.co.uk/p/draper-n144-250mm-pair-coil-spring-compressors/ https://www.amazon.co.uk/Draper-14173-Coil-Spring-Comssors/dp/B0001K9Q2W/ref=sr_1_1?dchild=1&keywords=draper+coil+spring+compressor&qid=1608912048&sr=8-1 https://www.ebay.co.uk/itm/1000kg-Macpherson-Strut-Coil-Spring-Compressor-Dumper-Extractor-Yolk-Protector-/263132309969?hash=item3d43e869d1 If you're using a spring compressor that might take the paint off, it might be worth cutting up an old bicycle/motorcycle inner tube to size and wrapping that round the coil spring to stop the paint being chipped off and exposing bare metal.

185/65R15 195/55R16 205/45R17 These three tyre sizes all have about the same outside diameter. 185/65R15 are the most comfortable size and the least expensive size. 205/45R17 are the least comfortable size and the most expensive size. However, 195/55R16 could be a good option for the Fabia MK2 VRS as their front discs are about 312mm. Michelin CrossClimate+ 185/65R15 92T/V XL https://www.blackcircles.com/order/tyres/search?width=185&profile=65&rim=15&wintertyre=1&manufacturer=michelin Michelin CrossClimate+ 195/55R16 91H/V XL https://www.blackcircles.com/order/tyres/search?width=195&profile=55&rim=16&wintertyre=1&manufacturer=michelin Michelin CrossClimate+ 205/45R17 88W XL https://www.blackcircles.com/order/tyres/search?width=205&profile=45&rim=17&wintertyre=1&manufacturer=michelin Blackcircles aren't listing any Alpin 6 in those sizes at the moment. Besides, it's often best to purchase winter tyres in the summer when the demand isn't so high.

VW Golf MK7 Nogaro Alloy Rims 7.5Jx18 ET49 5/112 57.1 https://volkswagen.7zap.com/en/rdw/golf+variant+4motion/golf/2016-746/6/601-601065/ 18" alloy rims are surprisingly heavy. Most are over 12kg each without the tyre. 225/45R17 on 7J rims would give a more comfortable ride than 225/40R18 on 7.5J rims and be less prone to kerbing and pothole damage. https://www.wheel-size.com/size/skoda/octavia/2009/ Skoda Octavia 2009 2.0TDi RS – Generation: 1Z [2005 .. 2012] [EUDM] – Power: 168 hp | 125 kW | 170 PS – Engine: I4, Diesel – Center Bore: 57.1 mm – Wheel Fasteners: Lug bolts – Thread Size: M14 x 1.5 – Trim Production: [2006 .. 2012] Tire Rim PCD 225/45ZR17 91W 7Jx17 ET54 5x112 2.5 225/40ZR18 91W 7.5Jx18 ET51 5x112 2.5 Skoda Octavia 2009 2.0TSi RS – Generation: 1Z [2005 .. 2012] [EUDM] – Power: 197 hp | 147 kW | 200 PS – Engine: I4, Petrol – Center Bore: 57.1 mm – Wheel Fasteners: Lug bolts – Thread Size: M14 x 1.5 – Trim Production: [2007 .. 2012] Tire Rim PCD 225/45ZR17 91W 7Jx17 ET54 5x112 2.5 225/40ZR18 92W 7.5Jx18 ET51 5x112 2.5

What is the diameter of your front brake discs? 340mm diameter front brake discs need at least 17" wheels. 312mm diameter front brake discs need at least 16" wheels. 288mm diameter front brake discs need at least 15" wheels. Star rims have a specification of 6Jx16 ET48 5/112 57.1 https://eshop.skoda-auto.sk/en_SK/alloy-wheel-star-16-for-octavia-iii/p/5E0071494A+8Z8 Ilias rims have a specification of 6.5Jx16 ET46 5/112 57.1 215/60R16 will bulge out more on 6J rims than 6.5J rims and therefore better protect the rims from kerbing damage. Fitting 215/60R16 to narrower 6J rims will improve the ride compared to fitting this size to wider 6.5J rims. If you have 340mm diameter front discs, 16" wheels won't clear the front brake calipers.

340mm = 1LA = OEM part number 1K0615301AD This 340mm front disc was also fitted to a 2008-2016 Superb MK2. It looks like Skoda raided their old parts bin for the MK3. http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/SUP/year/2008/drive_standart/632/hg_ug/615/subcategory/615047/part_id/0/lang/e Brembo have a drilled disc version, but it's twice the price of the standard version. https://www.autodoc.co.uk/car-parts/oem/1k0615301ad?supplier[0]=65

I suspect the 140kW/190PS Superb MK3 has 340mm diameter front discs, in which case 16" wheels won't fit. See below at the wheel-size.com entry for this model. Notice that 16" wheels aren't listed as an option. https://www.wheel-size.com/size/skoda/superb/2016/ Skoda Superb 2016 2.0TDi – Generation: 3V [2015 .. 2019] [EUDM] – Power: 188 hp | 140 kW | 190 PS – Engine: DDAA, I4, Diesel – Options: SE L, Sportline, Ambition, Style, L&K, Executive – Center Bore: 57.1 mm – Wheel Fasteners: Lug bolts – Torque: 140 Nm – Thread Size: M14 x 1.5 – Trim Production: [2015 .. 2019] Tire Rim PCD 215/55ZR17 94W 7Jx17 ET40 5x112 2.3 / 2.1 235/45ZR18 94W 8Jx18 ET44 5x112 2.4 / 2.2 235/40ZR19 96W 8Jx19 ET44 5x112 2.4 235/35ZR20 95Y 8Jx20 ET40 5x112 2.6 / 2.4

Bilstein 36-199648 corresponds to OEM part number 1K0511115BS Bilstein 36-199655 corresponds to OEM part number 1K0511115BT According to Kilen's online catalogue, the Octavia MK2 RS hatchback uses 1K0511115BS and the Octavia MK2 RS estate uses 1K0511115BT Octavia MK2 RS Hatchback https://web.tecalliance.net/kilen/en/parts/176/63127/detail?targetType=cars&targetId=26623&typeNumber=26623&targetCountry=AT&groups=188#@brc/brands:Car;targetType:cars;mandator:kilen/assem:SKODA%20OCTAVIA%20II%20(1Z3)%202.0%20TDI%20RS;targetType:cars;mandator:kilen;targetId:26623;typeNumber:26623;targetCountry:AT/lnkparts:Coil%20Springs;targetType:cars;mandator:kilen;assemblyGroupId:100113;targetId:26623;typeNumber:26623;targetCountry:AT;groups:188;brands:176;pf:2;page:0/detail:63127;brandId:176;articleNo:63127;mandator:kilen;targetType:cars;targetId:26623;typeNumber:26623;targetCountry:AT;groups:188 Octavia MK2 RS Estate https://web.tecalliance.net/kilen/en/parts/176/63128/detail?targetType=cars&targetId=26624&typeNumber=26624&targetCountry=AT&groups=188#@brc/brands:Car;targetType:cars;mandator:kilen/assem:SKODA%20OCTAVIA%20II%20Combi%20(1Z5)%202.0%20TDI%20RS;targetType:cars;mandator:kilen;targetId:26624;typeNumber:26624;targetCountry:AT/lnkparts:Coil%20Springs;targetType:cars;mandator:kilen;assemblyGroupId:100113;targetId:26624;typeNumber:26624;targetCountry:AT;groups:188;brands:176;pf:2;page:0/detail:63128;brandId:176;articleNo:63128;mandator:kilen;targetType:cars;targetId:26624;typeNumber:26624;targetCountry:AT;groups:188 If you have the estate, you could use the slightly softer 1K0511115BS version if you don't normally carry a heavy load. Some aftermarket brands only sell one spring to replace both 1K0511115BS and 1K0511115BT OEM part numbers. 1K0511115BS has 1 blue dot and 2 yellow dots. 1K0511115BT has 1 blue dot and 3 yellow dots. http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/OCT/year/2013/drive_standart/663/hg_ug/511/subcategory/511020/part_id/0/lang/e

Good drivers don't use their brakes much. They read the road ahead and keep a good distance between them and the car ahead. Overuse of the brakes not only wastes fuel but causes rapid wear of the brakes. 256mm front discs means that 14" tyres are an option. 288mm front discs means at least 15" tyres are required.

256mm diameter front discs weigh about 5.1kg each 288mm diameter front discs weigh about 7.2kg each That's a big difference to unsprung weight. 256mm and 288mm Brembo front discs https://www.autodoc.co.uk/car-parts/brake-disc-10132/skoda/fabia/fabia-nj3/108657-1-2-tsi?supplier[0]=65&criteria[100]=VA

Looking at what both engines will remap to gives an idea of whether the hardware differences are big or small. With the difference in the remapped power outputs of the 245PS and 280PS engines being small, it would suggest that the hardware differences are also small. Another example is the 90PS and 110PS 1.2TSI engines. These engines both remap to about the same power output which would suggest that they have the same hardware. Both engines only remap to around 100PS to 105PS per litre of engine capacity, which would suggest the hardware on these engines is quite modest. However, modest hardware can sometimes give good low down power and driveability.

245PS/370Nm remaps to 302PS/450Nm@1750rpm https://www.dtintecno.de/cars/2-0-tsi-rs-180-kw-245-ps:14432 280PS/350Nm remaps to 332PS/430Nm@1900rpm https://www.dtintecno.de/cars/2-0-tsi-206-kw-280-ps:14441 It looks like the remapped 245PS engine has the best torque. Not only 20Nm more, but produced from 150rpm lower down the rev range. However, you would need to see the torque curve of both remapped engines to get the full picture. So according to dtintecno, the remapped 245PS engine has a whopping 100Nm more torque than the standard 280Nm engine.

This is just to give you an idea of what a 90PS 1.2TSI can be remapped to. Maximum torque comes in at a relatively low 1600rpm on the 1.2TSI engine, whereas the smaller 1.0TSI needs 2000rpm before it will deliver the beans. I've no idea what the gearing is on either car, but let's say it's 25mph/1000rpm. This would translate to maximum torque being available in top gear at 40mph on the 1.2TSI, but not until 50mph on the 1.0TSI. SKODA FABIA NJ 2014 - 1.2 TSI 66 kW / 90 PS, 160 Nm (Serie) Leistungssteigerung Hubraum 1197 ccm Drehmoment 230 Nm bei 1600 U/min Mehrleistung 30 PS / 22 kW, 70 Nm Höchstgeschwindigkeit V-Max aufgehoben Verbrauch (Differenz) 0 bis 1 Ltr. https://www.dtintecno.de/cars/1-2-tsi-66-kw-90-ps:14650

Standard tyre and rim sizes for the Fabia MK3 1.2TSI 110PS 6Jx15 ET38 185/60R15 7Jx16 ET46 215/45R16 7Jx16 ET46 215/40R17 http://www.oemepc.com/skoda/parts_lst/markt/CZ/modell/FAB/year/2016/hg/6/catalog/sk/drive_standart/797/lang/e 185/60R15 is a much cheaper tyre size than the 215/45R16 and 215/40R17 options. You can also get cheap steel rims in the 6Jx15 ET38 size. Alcar 7760 Steel Rims 6Jx15 ET38 5/100 57.1 https://www.autodoc.co.uk/spares-search?keyword=7760&brandNo[0]=100470 Skoda Fabia 2017 1.2TSi – Generation: Mk3 NJ [2015 .. 2021] – Market: EUDM – Power: 109 hp | 81 kW | 110 PS – Engine: CJZD, I4, Petrol – Options: Ambition, Style, Monte Carlo – Center Bore: 57.1 mm – Wheel Fasteners: Lug bolts – Torque: 120 Nm – Thread Size: M14 x 1.5 – Trim Production: [2015 .. 2017] Tire Rim PCD 215/45R16 86V 7Jx16 ET46 5x100 2.2 185/60R15 84H 6Jx15 ET38 5x100 2.1 215/40R17 87V 7Jx17 ET46 5x100 2.2 https://www.wheel-size.com/size/skoda/fabia/2017/

165/70R14 tyres fitted to 5Jx14 ET35 5/112 57.1 rims are a standard fit on the Fabia MK2. Alcar 5210 5Jx14 ET35 5/100 57.1 Steel Rims https://www.autodoc.co.uk/alcar/14750466 You can also fit 185/65R14 tyres to these rims if your country's laws allow it. The outside diameter of 185/65R14 tyres is the same as 195/55R15 and 205/45R16, but the ride is much more comfortable, and they are a much cheaper tyre size.

The hatchback and estate rear springs will be physically almost identical. They will both have an outside diameter of about 112mm and are interchangeable, ie. they will physically fit on either car. Spring Design Coil spring with constant wire diameter Fitting Position Rear Axle Thickness 11,75 mm Length 330 mm Outer diameter 112 mm Weight 1,85 kg https://web.tecalliance.net/gkn/en/parts/1/86744/detail?query=1K0511115BS&numberType=1&oe=1K0511115BS&groups=188#@brc/search:Search%20by%20any%20number%201K0511115BS;mandator:gkn;query:1K0511115BS;groups:188;brands:1;pf:2;page:0/detail:86744;brandId:1;articleNo:86744;mandator:gkn;query:1K0511115BS;numberType:1;oe:1K0511115BS;groups:188 The Skoda online parts catalogue lists eleven different rear springs for the lowered/sport suspension Octavia MK2 as follows: 1K0511115BQ Model data: PR-1JC+0YC 1K0511115BR Model data: PR-1JC+0YD 1K0511115BS Model data: PR-1JC+0YE 1K0511115BT Model data: PR-1JC+0YF 1K0511115CA Model data: PR-1JC+0YG 1K0511115CD Model data: PR-1JC+0YK 1K0511115CE Model data: PR-1JC+0YL 1K0511115DG Model data: PR-1JC+0YH 1K0511115DH Model data: PR-1JC+0YJ 1K0511115GB Model data: PR-1JC+0YA 1K0511115GC Model data: PR-1JC+0YB Notice that alongside each OEM number is a PR code. This is a build code, ie. what the car left the factory with. Some cars have a build codes sticker in the boot somewhere. Not all the build codes/PR numbers are listed on this boot sticker so may or may not show the PR code for what rear springs the car left the factory with. You may be able to ask a local Skoda dealer for a printout of all the PR codes. The PR codes will show things like what springs, shock absorbers, brake discs, etc. the car left the factory with. If for example, your car had PR code 1JC+0YE then that would mean that your car left the factory with 1K0511115BS rear springs. Here's another way of finding the OEM number of your rear springs. If your car has original rear springs, you can read the coloured dots and by reference to a chart find the OEM number of the rear springs. For example, if your rear springs have 1 blue dot and 1 yellow dot, then that would mean that your rear springs have OEM number 1K0511115BS. The Skoda online parts catalogue lists the coloured dots alongside the OEM number of the rear springs. http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/OCT/year/2010/drive_standart/663/hg_ug/511/subcategory/511020/part_id/2561497/lang/e You can use the gknautomotive online spring catalogue to see a list of cars that the above eleven OEM springs were fitted to out of the factory. For example, seaching for the 1K0511115BQ OEM number in the search box on the link below (ie. gknautomotive online catalogue) brings up the vehicle linkage. Click on VW or whatever other make it lists and you will see a list of cars that came out of the factory with that spring. 1K0511115BQ for example, lists lots of VW Golf MK5 hatchback 3-door cars with sports suspension. So for a Skoda Octavia MK2 hatchback with sports suspension, eg. RS model, that spring would probably be a little too light. https://web.tecalliance.net/gkn/en/parts/1/87127/detail?query=1K0511115BQ&numberType=1&oe=1K0511115BQ&groups=188#@brc/search:Search%20by%20any%20number%201K0511115BQ;mandator:gkn;query:1K0511115BQ;groups:188;brands:1;pf:2;page:0/detail:87127;brandId:1;articleNo:87127;mandator:gkn;query:1K0511115BQ;numberType:1;oe:1K0511115BQ;groups:188

Skoda Online Parts Catalogue (this is for the Superb MK2 as that catalogue only goes up to 2016 models) http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/SUP/year/2016/drive_standart/768/hg_ug/011/subcategory/11010/part_id/2546939/lang/e Skoda Online Parts Catalogue (this is for the Octavia MK3) http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/OCT/year/2016/drive_standart/753/hg_ug/011/subcategory/11010/part_id/2546939/lang/e Maybe try a deflated wheel and try and work out how much you have to play with. I would have thought it was designed to take a flat tyre. It looks like the Superb MK3 whirly plastic screw might be shared with other models such as the Octavia and the Superb, as they sometimes share the same OEM part number. What OEM part number is your whirly plastic screw? (It should be moulded into the plastic) The OEM part number will look something like this: 1K0803899D The Yeti, which uses tyre sizes including 215/60R16 and 225/50R17 has OEM part number 1K0803899E for its whirly plastic screw. Notice how similar this number is to the Octavia MK3 and Superb MK2 OEM number with just the last digit being changed from D to E. This could represent a small increase in length to account for the wider tyre sizes that the Yeti uses compared to the Octavia MK3 and Superb MK2...which used tyre sizes including 195/65R15 and 205/55R16.