Rim size changes.

[Darrell1]

Hi,

Just purchased a Yaris Cross with Dynamic trim which comes with 18'' as standard. I'm now aware the Design trim comes with 17'' rims and offers better MPG. Would it be possible to change to 17'' from 18'' and see a change in MPG, with out affecting gear ratio etc? Thanks.

[FROSTYBALLS]

Would have thought any change for 18 to 17 as regards mpg would be minimal. You will need to inform your insurer of the change in spec, and they may consider it a modification.

[Darrell1]

Thank you. Just wondered because next trim level down has 17'' wheels and has better MPG around 8MPG, considering the only difference between specs is the trim level. Same 1.5 hybrid engine etc? Thank you.

[FROSTYBALLS]

Presumably the figures you're looking at are the official consumption figures achieved from the WLTP testing regime, which, although more accurate than the previous testing system still doesn't truly represent what owners may achieve.

The insurer will expect it to have 18 inch rims as that is the standard spec for that trim level - if you change the rims, the change needs to be declared.

[Darrell1]

Thank you Mike. Informing the insurer would not be an issue. I drive about as frugal as you can get so just finding if it would be worth downsizing. 

[Cyker]

You'll see a more noticeable in comfort and NVH going from 18's to 17's (Or 16's if that's a thing??).

MPG is harder to say - Officially the Mk4 Yaris has better mpg figures for the smaller rims too, but I went from 17's to 15's and while I think the mpg is better, it's hard to say for sure as the difference seems small enough to be lost in the variations caused by my ahem spirited driving style.

I was getting tank-average mpg in the low-mid 70's on the 17's at the time, and after the change my log shows slightly higher (Like, by 1-2mpg) but still same ballpark. It climbed to the 80's after a few weeks, but IIRC that was when the weather started getting hotter, so likely that's more the weather than the rims!

Has been dropping back toward the low-mid 70's as it's gotten colder.

[Darrell1]

Thank you Cyker.

[Aygolite]

On 10/29/2021 at 3:58 PM, Darrell1 said:

Hi,

Just purchased a Yaris Cross with Dynamic trim which comes with 18'' as standard. I'm now aware the Design trim comes with 17'' rims and offers better MPG. Would it be possible to change to 17'' from 18'' and see a change in MPG, with out affecting gear ratio etc? Thanks.

My insurance company is quite good when it comes to changing tyre sizes. They say as long as it doesn't increase the performance of the car, and one size different from standard is not a problem.

According to wheel-size.com the Yaris Cross has the following tyre and rim options:

205/65R16 6.5Jx16 ET45 5/114.3 60.1

215/55R17 7Jx17 ET50 5/114.3 60.1

215/50R18 7Jx18 ET50 5/114.3 60.1

You could even consider the below non-standard 15" option, although you would have to check that a 15" rim will clear the front brake calipers (it probably will because the Yaris Cross doesn't have a hugely powerful engine so is unlikely to have massive front brakes):

205/70R15 6Jx15 ET45 5/114.3 60.1

The below Yokohama G015 Geolander AT is an all-terrain tyre, and would probably suit the image of the Yaris Cross quite well. Being an all-terrain tyre it will have noticeably more grip in the mud and off-road than a smooth summer tyre.

Compared to the low profile 215/50R18 tyre, the much higher sidewalled 205/70R15 would make the ride a lot more comfortable and softer. With the 205/70R15 tyre, you would probably have to over-inflate it by at least 10psi to get even close to the hard ride of the 215/50R18 tyre. Another advantage of 205/70R15 over 215/50R18, is that the 15" tyre is about half the price of the 18" tyre.

Yet another advantage of 15" rims over 18" rims is weight. I expect the 15" rims would be about 4kg lighter than the 18" equivalents. So about a 16kg weight saving on rims alone, 20kg weight saving if you carry a full-size spare in the car.

The outside diameter of these four tyres are as close to each other as makes no difference, ie. less than 0.8% difference, or no more than 2.45mm difference in radius.

Yokohama G015 Geolander AT (All-Terrain) 205/70R15 96H

https://www.camskill.co.uk/m53b0s2481p148166/Yokohama_Tyres_Car_Yokohama_G015_Geolander_AT_Yokohama_G_015_-_205_70_R15_96H_TL_Fuel_Eff_%3A_E_Wet_Grip%3A_C_NoiseClass%3A_B_Noise%3A_70dB

6Jx15 ET45 5/114.3 60.1 steel rim from 1990-2000 Toyota MK2

https://www.oponeo.pl/felga-stalowa/magnetto-wheels-mw-r1-1975#21663158

TOYOTA YARIS CROSS XP210 [2020 .. 2024]1.5 HEV

114 hp

LADMEUDM

• Generation: XP210 [2020 .. 2024] [JDM] 
• Production: [2021 .. 2023]
• Sales regions: Central & South America, Europe, Russia+, Middle East, North Africa, Oceania
• Power: 114 hp | 85 kW | 116 PS
• Engine: 1.5 L, M15A-FXE, I3 , Hybrid
• Trim Levels: Icon, Design, Excel, Dynamic, Premiere Edition

• Center Bore / Hub Bore: 60.1 mm
• Bolt Pattern (PCD): 5x114.3 (5x4.5)
• Wheel Fasteners: Lug nuts
• Thread Size: M12 x 1.5
• Wheel Tightening Torque: 103 Nm

TIRE	RIM
OE205/65R16 95H	6.5Jx16 ET45
OE215/55R17 94V	7Jx17 ET50
OE215/50R18 92V	7Jx18 ET50

https://www.wheel-size.com/size/toyota/yaris-cross/2021/#region-eudm

[Mojo1010]

@Cyker Tagging u in to say....

So this afternoon I saw a local driving instructor with a MK4 Yaris excel in titanium bronze - nice colour (a recent changed of car) at a supermarket car park. Went over to say hi and asked how he is finding the tyre profile on the 17". He told me he is struggling with it lol. I kinda dodged a bullet then 😅

So I told him to look into whether it can be changed into a 205/50/17, as long as it does not under read on the speedo. He didn't know original profile can be changed. Also told him I was getting the design with better tyre profile to absorb the bumps and bad roads, and to change it to 205/55/16 after. So the moral of the story is, the excel tyre profile is bad 🙂 dread to think what the GR on 18" is like 🥴

[Cyker]

I just hope the GR seats have good shock absorption!  

Every day when I look at the road surface, I'm so glad I changed to the 15's!!

[Mojo1010]

Seen a Porsche panamera locally, tyres were 305/ 35 or 40/ 21 😳. It's about £300 a premium tyre without fitting. Thanks but will spend that on a premium set for the Yaris 😅