235 40 R18 Tyres ?

[SiRS2000]

Just a thought for all those looking at 18 in tyre options, I have just looked at T5 monkeys thread ref the new S60 naughty track day he went on, locking at the pics there is a nice new C70 with a option wheel fitted, also a option on S40 & V 50, any way the tyre size fitted to the C70 is 235 40 R18.

So I am thinking, C70 same floor pan, brakes etc as S40 & V50, so any one else recon these will fit.

I know some have been looking at 225 40 R18 to replace the 215 45 R18 so please share thoughts if this is a viable option too.

[SiRS2000]

I have just looked on www.etyres.co.uk 235 40 18 a tad more expensive than 225 40 18 but still considerably cheaper than 215 45 18.

Also if you calculate the % ratio of the tyre wall the 235 is a lot closer than 225, I think I may have struck gold hear as long as 7.5 wide rims will take 235 profile.

[t5_monkey]

Originally Posted by SiRS2000

I have just looked on www.etyres.co.uk 235 40 18 a tad more expensive than 225 40 18 but still considerably cheaper than 215 45 18.

Also if you calculate the % ratio of the tyre wall the 235 is a lot closer than 225, I think I may have struck gold hear as long as 7.5 wide rims will take 235 profile.

Those wheels were lovely.

I've got 225's no problems on 7.5 inch rims, as long as your rolling radius is within a few percent of stock you should be fine.

225/40/18 would be fine on those rims - there's only 10mm in it anyway tread width wise between those and the 235.

[tayandre]

I have these 18" wheels on my C30. I'd love to ditch them for a set of 17", the ride is rubbish and the tyres expensive. Iit doesn't drive any better than the 17" wheels on a C30 1.6D I had as a courtesy car.

Anyone up for a swap?

I don't think the larger tyres used on C70 will fit C30/S40/V50, the C70 has a much wider track. I suspect if you put larger tyres on the smaller car you will get contact between rubber and wheel arch.

[t5_monkey]

Hi Tayandre I've got a set of Standard S40 17" wheels from mine just sitting on my Balcony not being used so I'd b happy to swap.

Here's a photo:



I've run 18x8.5 ET 40 on my so I'm pretty sure the ones on that C70 will fit no problems.

Some minor bubbling around the the wheel valve and some kerbing - but I know a great place that will refurb them for you to perfection for £140 (got my OZ wheels done there.)

4 tyres on - 2x Brabarus with about 7mm tread, 2x Vredstein Ultracs with 3mm

PM me if you're interested in discussing a swap of some kind and let me know what style yours are.

Cheers, Ben

Originally Posted by tayandre

I have these 18" wheels on my C30. I'd love to ditch them for a set of 17", the ride is rubbish and the tyres expensive. Iit doesn't drive any better than the 17" wheels on a C30 1.6D I had as a courtesy car.

Anyone up for a swap?

I don't think the larger tyres used on C70 will fit C30/S40/V50, the C70 has a much wider track. I suspect if you put larger tyres on the smaller car you will get contact between rubber and wheel arch.

[tayandre]

Thanks for the offer. If they were the 5 spoke alloys that come with the regular R-Design I'd jump at it. Not sure if these would suit a C30 RD. Will have a scout about to see if there are any pics on the web of a C30 with this wheel combo.

The wheels on mine are the same as the S60 pic above, think they are called 18" Midir (Diamond Cut/Light Grey) Alloy Wheels.

Link here

Wonder does the ECU need re-programmed when you change wheel size so the speedo and ESP work correctly?

[t5_monkey]

Originally Posted by tayandre

Thanks for the offer. If they were the 5 spoke alloys that come with the regular R-Design I'd jump at it. Not sure if these would suit a C30 RD. Will have a scout about to see if there are any pics on the web of a C30 with this wheel combo.

The wheels on mine are the same as the S60 pic above, think they are called 18" Midir (Diamond Cut/Light Grey) Alloy Wheels.

Link here

Wonder does the ECU need re-programmed when you change wheel size so the speedo and ESP work correctly?

It'll work fine without a reprogramme, may be a little out.

Try a rolling radius calculator to help out: http://www.kouki.co.uk/utilities/vis...ize-calculator

Your dealer can reset it to '17' inch wheels.

Since those have a lower rolling diameter, you'll notice the car feels a bit quicker, due to 2-3% lower gearing!

[rustydonkey]

The rolling radius of the 235/40/18 is almost the same as 215/45/18. It's only going to be 10mm extra width on the inside of the arch to worry about and if people are running 225/40/18 with no problems then its only 5mm.

Decisions decisions, i was just about to order Continental sport contact 3's in 225/50/18.

[t5_monkey]

Originally Posted by rustydonkey

The rolling radius of the 235/40/18 is almost the same as 215/45/18. It's only going to be 10mm extra width on the inside of the arch to worry about and if people are running 225/40/18 with no problems then its only 5mm.

Decisions decisions, i was just about to order Continental sport contact 3's in 225/50/18.

go with the widest tyre you can.... it might not sound much an extra 20mm of tread but...

... that is however 9% extra surface area and grip

[rustydonkey]

I've priced up the Continental sport contact 3's, the 225/40/18's are £132 each fitted and 235/40/10 are £174 each fitted. That's an expensive 10mm, think I will go with 225/40/18.