GSI Tyres - 215/45/17 or 225/45/17 ???

[user998]

Hi All,

About 6 months ago I replaced one of my GSI Tryes with an £80 cheap Falken, I currently have about 2ml remaining - this is now the same as all of my other tyres.

Rather than pay £130+ for NCT5 or £80 cheap tyres that don't last, I have been reading on here that other members are using 225/45/17 tyres.

On "another" VX site someone has suggested remaining with 215 but using 45 for the profile.

Which is the better option, and will either potentially upset handling, sppedo, etc.

Thanks in advance

[m8internet]

I'd check with original specification, but I believe you should be using 225/45R17
The 215 width is 215/50R17

I've dumped the NCT5 on 215/50R17 in favour of GSD3 225/45ZR17 and although they are not as forgiving at low speed, overall they are pretty similar
Wet weather grip also feels superior, just waiting for the existing 215/50R17 on the fronts to wear out now...

[Gsi3.2]

you can go to 225's without affecting anything to do with the speedo and they are significantly cheaper with with a wider choice of tyres..

it's altering the sidewall profile that affects the speedo reading , so stick to the factory profile, or get the speedo altered to the new tyre profile at Vauxhalls ( who will charge you £40 to do it)..

we ran Mrs GSi's signum on 225's, and didn't notice any difference to the 215's..

[user998]

Hi Mark,

Just to confirm, you are advising sticking with the 50 profile and increase to 225 i.e. 225/50/17 ?

cheers

Ian

[Gsi3.2]

yep, thats what i'm saying...it won't affect your rolling radius, so it won't affect your speedo at all..

[Gsi3.2]

http://www.miata.net/garage/tirecalc.html

thats the tyre size calculator that will guide you on you comparisom of tyre sizes and how they will affect you speedo..cross section of the tyre is only down to the max safe size the rim will carry..you can go to 235, but 225 is really the max..

[Duncan]

Hi Mark,

Just to confirm, you are advising sticking with the 50 profile and increase to 225 i.e. 225/50/17 ?

yep, thats what i'm saying...it won't affect your rolling radius, so it won't affect your speedo at all..

You sure Mark? Shouldn't it be 215/50/17 (fited as standard) or 225/45/17 as they are the two sizes of 17 listed by Vx, and are within a couple of % of each other for rolling radius.

Ian - when I had 17s I switched from 215/50/17 to 225/45/17 and the handling felt a bit more sure footed, but the main reasons were that there is a bigger selection of tyres in that size/profile and they are a bit cheaper for the same tyre that was available in 215/50/17.

D

[m8internet]

See my original reply
The Vectra C file I have shows 215/50R17 as the VX standard fit
225/45R17 is the alternative tyre

[user998]

Cheers everyone, much appreciated! I guess I will go for four 225/45/17 tyres. Any recomendations for good combination on price/quality? On my old Vectra B (2.6) I found that best all rounder for Dry, Wet, longevity were Dunlop Sports (Michelin and Continnental were good in dry but found not as good in wet and tended to wear out quite quickly)

cheers

[m8internet]

I do agree, the Michelin is a great dry weather, high mileage tyre, but you have to take care in the wet

I'm on the Good Year GSD3 F1 XL 225/45ZR17 94W
£90 each fitted, compared to nearly £150 NCT5 XL 215/50R17 95W
The tread pattern is nice too!