Will fitting 215/35-18's ruin the ride quality?

[humph]

I have finally decided on some new alloys and am looking at Rota Subzero, 18*7.5, ET 45, about 8kg. These will come with 215/35-18 tyres which are 608mm diameter as opposed to the 205/45-17 (616mm) i run at the moment. Looks as though there is going to be about 12-16mm less rubber between the rim and the road, is this going to have a huge effect on my ride quality? The new tyres will not be RF's which my current ones are. Current car is 06 spec Cooper on SS+.

Without wanting to cloud the issue I will probably be fitting Eibachs as well.
Would be grateful for anyones experiences.

Simon

[nylo]

I know this probably isn't a major help, but I did notice a difference when I changed from 17" RFs to 18" RFs. I'd forgotten how noticible it was until Banana Pancakes got her new S with 17s. Having said that though, I've got Works suspension too. It's not unbearable though, plus you get used to it!

I think you'll notice a difference, but it won't be unbearable, the lack of rubber being offset slightly by non RF tyres. Plenty of guys on here are running that, maybe you could even speak nicely to someone near you, get a drive to see for yourself?

[OZChris]

Hi, I have 215/35-18 tyres with 18 x 7.5 ET40 wheels and I don't think that the ride quality has been ruined. Actually I think the ride got better when I recently lowered my S with KONI Sport springs. Good Luck.

[Hyper Active]

Quote: Originally Posted by Humph (original)

I have finally decided on some new alloys and am looking at Rota Subzero, 18*7.5, ET 45, about 8kg. These will come with 215/35-18 tyres which are 608mm diameter as opposed to the 205/45-17 (616mm) i run at the moment. Looks as though there is going to be about 12-16mm less rubber between the rim and the road, is this going to have a huge effect on my ride quality? The new tyres will not be RF's which my current ones are. Current car is 06 spec Cooper on SS+.

Without wanting to cloud the issue I will probably be fitting Eibachs as well.
Would be grateful for anyones experiences.

Simon

Everyone on here who has SS+ and has changed from 17" runflats to 18" non runflats, has reported an improvement in ride quality, a reduction in tyre noise and improved grip, both wet and dry. The sidewalls on the runflats are very stiff compered to normal tyres.

[humph]

Thanks for the opinions so far guys. Anymore?

[MarkW19]

I noticed a big increase in roadnoise when going from 215/40/17 goodyear F1s to 215/35/18s. Also the ride got quite a bit harder/crashier.

But I didn't get the car to be quiet or comfortable...I just accept it's never going to be either. As such, I fitted KW v2 coilovers a few weeks back which have made it a bit harder still (even on a "soft" setting), but boy does it transform the car's handling!!

Bottom line: It will increase roadnoise and make the ride harder, but how much of a problem that is is down to you. It's all subjective and personal

[Bilbo Baggins]

My dealer installed a set of Eibach spring in a customers car and had to take them back out because of the brutal ride. I wouldn't do both, tires and springs, at once. Try one at a time, then you will know which caused the problam and which to remove.

[jayex]

Quote: Originally Posted by Hyper Active (original)

Everyone on here who has SS+ and has changed from 17" runflats to 18" non runflats, has reported an improvement in ride quality, a reduction in tyre noise and improved grip, both wet and dry. The sidewalls on the runflats are very stiff compered to normal tyres.

i would second that

[M1OY CS]

im running 215/35/18 O.Z super leggeras with toyo proxes and the ride is harsh. I must say though compared to the 17s with runflats the handling is much improved. My view is the handling and ride quality are improved when on good road surface. When you a bad patch its much more noticable through the suspension especially at high or very low speeds. Also when you hit a pothole with the 18" you will feel it alot more and also feel your doing the suspension alot more damage than if you had the 17".

Thats just my view thought. Oh and im runnin stock sups SS+

[humph]

Right then, another thread has just reminded me I wanted to update this thread with my experiences since fitting my 18 inch alloys. In the end I bought a set of 18" Rota subzero with Toyo Proxes 215-35-18 & I love them, I have also had the Eibachs fitted. The mods were done in stages, rims first, Eibachs a few weeks later.

Rims only - Having changed my 17" bullets and RF tyres for 18" non RF I have to admit I was pleasantly suprised by the ride quality. More road noise yes, but the ride itself really wasn't any harder. Handling doesn't seem to have been effected either but the alloys I bought are very light (about 7.8kg at 18"). I recon the handling would suffer if the alloys were heavy, tramlining and the likes.

Rims & Springs - The Eibachs made the ride harder than it was previously. You can now feel the road surface through the seat. Pot holes are best avoided but minor things like manhole covers (if the haven't sunk to far) are not a problem. Wouldn't recommend this comination if you have back problems though especially on long journeys. My car is a 56 plate so no rattles as yet, but in my previous 03 I'm sure it would have been very noisy in the cabin (squeek, rattle, crash).

On the whole am very pleased.

The one thing I will say is I have wrecked one wheel already (4 days in). Nothing to do with pot holes as such as the rim protector on the tyres does quite a good job. The problem is with the face of the rim which can get damaged easily as the tyres don't protrude out further than the rim. The incident was unfortunate but has been sorted. You just need to be careful of the face of the wheel.