Improving Ride Quality By Changing From 19's To 18's

[TheBlondeFella]

So, I need so help with improving my ride quality by changing from 19 inch wheels to 18 inch wheels rather than by changing the suspension. I have a bog standard, low mileage 2016 Mk7 R with DCC (standard camber).

To date since buying the car in 2016 I’ve run the flowing wheels all in 19’s;

• OE Pretoria: 19 x 8 - et50 - The Prets were fine but I wanted something a little different even after I had the colour changed.
• Neuspeed Rse10: 19 x 8 - et45 - I had a love / hate relationship with the Rse10s and in the end decided they just weren’t for me.
• Motec Ultralight: 19 x 8.5 - et43 - I buckled 3 of the Motec Ultralights in less than 12 months and despite these looking exactly how I wanted after having them refurbed in bright silver, they were obviously either too light or ‘made of cheese’ so they had to go.
• Revo RF019: 19 x 8.5 - et45 - Currently on my car with no issues at all.

I'm so sick of the quality of the UK roads and the ride quality of my car I'm now I'm going to swap the wheels again this time going down to an 18 inch wheel in the hope of an improved ride qaulity. I'm looking at either the Neuspeed rse11r in 18 x 8.5 et45 or the Revo RFO 18 x 8 et45. I'd prefer the Neuspeeds as they come in 8.5 width but in the UK they are almost double the price of the Revos so have yet to make up my mind.

The help I need is with tyre size as I definitely do not want to rub in any circumstances. I currently only use the car for fast road weekend outings and do one trip the the Nurburgring in Germany a year where tyre rubbing is definitely not a good idea.

• VW O.E fitment for a 19 inch wheel on a Mk7 R is : 235 / 35 / 19 which has a 82.25mm high side wall and a tyre diameter of 647.1 mm
• VW O.E fitment for an 18 inch wheel on a Mk7 R is : 225 / 40 / 18 which has a 90mm high side wall and a tyre diameter of 637.2 mm

So just by going from a 19 to an 18 with OE tyre spec. you get 7.75 mm more of tyre side wall cushioning and almost a 5mm arch gap loss which effectively makes the car look lower on 18’ compared to 19’s!

In theory, you’ll also get marginally increased acceleration as well due to the smaller overall rolling circumference and lower combined tyre and wheel weight (only with aftermarket wheels as a 19 Pret weighs less than an 18 Cadiz).

I guess that’ll be by they say “19’s for show and 18’s for go”. Who knew!

I’ve worked out the following which I hope everyone will agree with is correct.

Tyre Size	Sidewall Height	Tyre Diameter
235 / 35 / 19 (VW OE)	82.25 mm	647.1 mm
225 / 40 / 18 (VW OE)	90 mm	637.2 mm
235 / 40 / 18	94 mm	645.2 mm
245 / 40 / 18	98 mm	653.2 mm
255 / 35 / 18	89.25 mm	635.7 mm

Looking at the above chart, if I go from a 235 / 35 / 19 (VW OE) to a 235 / 40 / 18, I would get a 11.75 mm more side wall cushioning compared to what I have now with a tyre diameter that would be between the OE Pretoria and OE Cadiz.

The question is; Is this to best option, or are there better options available with guaranteed no tyre rub?

I seen from another post that @Karthoum is using a 255 / 35 / 18 tyre but I have serious concerns that this will rub as I’ve heard stories of 245 / 40 / 18 tyres rubbing through inner wheel arches.

 

[nomunic]

I run 17s with 235-45-r17but it didn’t help ride quality. My brothers 535i with rubber bands for tires on 19s is extremely comfortable. I think a lot of comfort comes from width of the tires, travel from the struts, and wheelbase length. Unfortunately, I’ve never sat in a comfortable mk7 but that’s not why I bought it.

I’ve had the stock 225 35 18 setup and it was terrible. I’ve also had wedssport 235 40 18 and it was also bad. I think you’d be better off trying to fit a 18 and getting some 235 45 18 at stock ride height.

 

[Maiden69]

The only car I had that felt great on small wall tire was my 2020 1SS/1LE, other than that they all felt like crap. The GTI with the OEM 225/40/18 felt tight as well. I am running Motegi 18x8.5et42 (45 would be better as I rub a little in the front at stock height with the fender screw mod done) with Michelin PS4S 245/40/18. The tire is a little taller than the OEM, but the wider track help it absorb the bumps better. I think it also has to do with how light this car is vs the Camaro, but I don't think I would run 19's at all on it.

 

[jay745]

17s are even better

 

[nomunic]

17s are even better

I felt no difference tbh

 

[golfdave]

I run 225/45R17 on a 17"x7J alloy..as per factory spec....except that as the alloys are low pressure formed (OEM were gravity formed), each complete alloy/tyre weighs 2kgs less than the OEM set up!..

I am on standard steel springs on factory OEM "sports" suspension....& find it runs well...

Having "rubber band" tyres has always been known to have bad comfort, as the tyre is the primary absorber of shocks....

Also the wider the tyre the worse the aero & fuel consumption & the worse the rotating mass of the wheels, as it is more likely to be further away from the centre line/kingpin alignment/tyre scrub...

Also the heavier the tyre/alloy, the worse the handling & reaction to potholes etc..

Then you have the differences caused by tyre types, eg summers, winters, all season. Then differences between brands, & finally differences due to load indexes & speed rating...


suspension design 1-0-1...

 

[scrllock]

235/40/18 does not rub with stock suspension, it is a very safe size. 255/35/18 does not rub either in my experience, whereas 245/40/18 does. Camber can negate this, or removing the top fender screw and tucking the liner. I would stick with 235s if you don't want to think about it/experiment.

 

[Oldfella]

we have pretty rough roads here and I found going to a kumho tyre made a difference in comfort and highway noise compared to the Goodyear tyre I had on

 

[IGM2019]

I switched from 235/35/19 to 245/45/17 and there is a huge improvement in ride quality and I don't have to worry about bending wheels any more. You'll need to do the fender screw mod though.