Suspension wheel & Tyre changes

[axel1990chp]

Howdy ladies and gents,
Short story;
I have a 2018 Leon Cupra 290. It’s getting to the point I want to start giving it the TLC it deserves regularly and it has lead me down a path I’ve no experience in. Upgrading/modding the suspension/wheels as the title suggests.

I’ve been suggested by a colleague to run a smaller wheel with a larger profile for the poor quality of the UK roads, I enter a minefield of knowledge that isn’t quite computing with me.

Secondly to this, when looking at the suspension of the car, I’ve thought is it worth upgrading to something a little more upmarket, perhaps with the option of minor height reduction (should I move forward with a smaller wheel) rather than OEM replacement parts?

Currently my tyres are 235/35/19 on the OEM 19 inch wheels. I find these to be fairly low profile compared to previous vehicles, so there are 2 questions essentially here.
1) if I were to drop to an 18 inch variation of wheel (same width etc) what profile would be a slight increase to this (so it still gives an overall lower profile of the car)?
2) as above, what profile would be required to keep the car at its exactly position when changing to an 18 inch? And is this feasible?

My suspension question I have more understanding of, however I question how the changes from the standard “mode adjustable” system is handled, is it a tricky affair? Do you lose mode adjustment completely with modification? (I refer to comfort as opposed to Cupra)

I appreciate these may be very simple questions but this is an unknown area for me - my Tyre and wheel knowledge is limited to mountain bikes I’m afraid!

Any knowledge, advice, guidance or answers is greatly appreciated!

The search feature on google hasn’t really helped my tiny brain

[tapkaJohnD]

Lots of tyre size calculators online, EG https://tiresize.com/tyre-size-calculator/

JOhn

[Tony1963]

What your colleague says isn’t that relevant. The question is whether you find the suspension too hard or not.

Your car, as standard from the factory, had an excellent vet up for all round requirements. If it’s too stiff on our roads for you, get a more suitable car, otherwise you’ll just ruin the whole point of the car. It’ll be a jelly on a plate in comparison with oem, and you’ll resent your choice every time you’re pressing on.

[paintman]

Are you unhappy with the current performance of the car & so you need to make changes?

It's all about what's best for you, not what a colleague thinks might be a good idea.

There's a lot to be said for using genuine parts for refreshing suspension - the car manufacturer has (hopefully!) spent a lot of time & money getting it right.

[budgie smuggler]

I must admit I've been thinking the same after dinging two rims on potholes.

I was thinking of going from 19 inch with 35 profile to 18 with 40 profile. Still low profile but a bit more sidewall to protect it.

The end result is almost exactly the same circumference.

[axel1990chp]

It’s not that I am dissatisfied by the performance, I just know it can be better!

The wheel Tyre situation has been suggested, the unsprung weight savings in my mind also light up the child in me, but seeing as though I aren’t tracking this car, i want to know if the benefit of a smaller wheel with a slightly thicker tyre is of even the slightest benefit.

Suspension is something I feel the car could 100% handle better, but it’s not something I want to dive into if the DCC style control is a pain or is lost through upgrading to a Bilstein package for example.

Thanks for the above screenshot, I’ve been playing with it myself since it was posted above, excellent tool!

Does anyone have any history with the above?

Thanks again in advance

[Dave.]

Check the prices of any prospective tyres before deciding on a wheel size.

You may find a certain size vastly more expensive than the next.

[MustangGT]

axel1990chp said:

Howdy ladies and gents,


I’ve been suggested by a colleague to run a smaller wheel with a larger profile for the poor quality of the UK roads, I enter a minefield of knowledge that isn’t quite computing with me.

Secondly to this, when looking at the suspension of the car, I’ve thought is it worth upgrading to something a little more upmarket, perhaps with the option of minor height reduction (should I move forward with a smaller wheel) rather than OEM replacement parts?

When going to a smaller wheel with higher profile tyre you are not making any change to the ride height of the car. Another poster talked about 235/23/19 being changed to 235/40/18. The difference in diameter is just 0.4%, in effect no change at all.

Another thing to consider is your insurance. Some companies refuse to cover modified cars, it often depends on whether or not the tyre/wheel combo is available on another trim level of the car model. Eg. I have a Jeep Cherokee running 18" wheels as standard. A lower trim level came with 17" wheels and the insurance company is happy with the 17" wheel/tyre combo provided the tyre size matches.

[E-bmw]

MustangGT said:

Another thing to consider is your insurance. Some companies refuse to cover modified cars, it often depends on whether or not the tyre/wheel combo is available on another trim level of the car model. Eg. I have a Jeep Cherokee running 18" wheels as standard. A lower trim level came with 17" wheels and the insurance company is happy with the 17" wheel/tyre combo provided the tyre size matches.

^^^^ Wot 'e said.

If you aren't going down the whole modified car route for a good reason don't bother.

Your normal insurance company will likely disavow you immediately as soon as you tell them of the changes & if you don't you are in a whole world of pain.