i30 Owners Club

MODIFYING OR DETAILING YOUR I30 => TYRES | WHEELS | BRAKES => Topic started by: Erikfr on July 17, 2021, 23:39:41

Title: Smaller wheels on GD
Post by: Erikfr on July 17, 2021, 23:39:41

I have found some wheels on toyota rims that are 5" 195 60 15, as a replacement for the 17" OEM wheels on my i30 GD crdi. Mostly because I want to improve ride comfort and accelleration. Will this cause problems given that they are outside the recommended tyre sizes (they are within the legal regulation where I live). And will they fit? They come from a toyota avensis.

Title: Re: Smaller wheels on GD
Post by: sundiz on July 18, 2021, 02:03:32

It all depends on rim specs. I believe Toyota hubs have smaller center hubs. So spacer might be required. Probably et value is off too. 195/65-15 is one of the original tyre sizes so I would get set of tyres in that size.

Title: Re: Smaller wheels on GD
Post by: The Gonz on July 18, 2021, 07:21:07

First thing to check is stud pattern. Can they bolt on? If so, to gain ride comfort you need more rubber profile.
However, to gain torque (what I equate to your desire for acceleration) you need less profile.
You can't have it both ways. To calculate profile, use  :link: Tyre Size Calculator (https://tiresize.com/tyre-size-calculator/)

Title: Re: Smaller wheels on GD
Post by: BrendanP on July 18, 2021, 23:46:11

As well as the stud pattern, you also need to consider the size of the centre boss on the hub that the wheel fits over. The wheel centre hole should match it as that's what centres the wheel on the hub. You could fit spacers but I don't know how effective they are at centreing the wheel, otherwise you're just reliant on the wheel studs. There is also the offset between the centre-line of the tyre and the mounting face of the hub, but that shouldn't be a problem if the 15" rims are narrower than the 17" rims you're taking off.

Title: Re: Smaller wheels on GD
Post by: Erikfr on July 19, 2021, 23:10:47

Aha, so when reducing the horizontal width of the rim the offset becomes less of an issue?

Title: Re: Smaller wheels on GD
Post by: Surferdude on July 20, 2021, 01:17:19

Quote from: Erikfr on July 19, 2021, 23:10:47

Aha, so when reducing the horizontal width of the rim the offset becomes less of an issue?

I'm not sure that's always the case.
Could be but I've never looked into it before.

What IS important is that you don't fiddle with the offset too much.

Fouling issues would be obvious once you've fitted them but steering geometry chnages are less obvious, except in handling characteristics, generally in dire situations.