downsizing from 19" to 18", which tyre size ?

[Kaamos]

Due to lovely french regulation I will probably have to change my current 19" for new 18".

I'm waiting for final decision but expect a set of 19" rota grids to appear in the for sale section shortly.

 

This being said, here's my tyre-related question, rim questions may come next :

 

My car is full stock except for wheels and BC coilovers.

I currently have 235/35/19 front and 275/30/19 rear

 

The only tyre sizes I may be allowed to get fitted in 18" are :

 

 

option A : 235/40/18 front 255/35/18 rear

option B : 265/35/18 front 295/30/18 rear

or a mix of both, so option C : 235/40/18 front 295/30/15 rear

 

I'm not even sure option or CB would fit without bodywork.....

 

What do you think ?

Edited October 22, 2018 by Kaamos
typo (see edit history)

[Karl M N]

Might need to have the arches rolled to fit the 295s.

 

Just curious, what is thisbfrench regulation and why does it force you to change wheel size?

[Kaamos]

that's what I thought as well, but I've seen several posts here and there tending to make me think that 295 would fit so I was wondering if someone here had some fitting and handling feedbacks.

 

About the regulation, long story short :

you were never allowed to fit any tyre-size to your vehicule in France, you must comply with a list of sizes that are acknowledged to be compatible with the stock size.

The list seems to have been slightly narrowed, and in the meantime the MOT has recently become harsher, checking points that they did not care about earlier (among which checking these bloody compatibility-lists when you don't run stock size).

 

So what was sometimes "tolerated" back then is not anymore...... me happy !

 

And on this list,the only compatible 19" size would be 275/30/19 front and 315/25/19 rear..... not sure I would want that... would you ?

[Delboy52]

Here's a handy calculator to at least keep your speedometer accurate. https://www.willtheyfit.com/

 

These are the standard OE Supra wheel and tyre settings to use as a baseline.

 

Front - Alloy 17 x 8j +50, Tyre 235 45 R17

Rear - Alloy 17 x 9.5j +50, Tyre 255 40 R17

Edited October 19, 2018 by Delboy52 (see edit history)

[Kaamos]

this I knew Dellboy but thanks for confirming.

As a sidenote and while you are talking about oem rims : I think I read somewhere in the owner manual that toy recommands square mount for winter tyres, so 235/45/17 all around..... isn't 235 a bit narrow on a 9.5j rim ?? or is it just my bad memory messing with inaccurate figures ?

Edited October 19, 2018 by Kaamos
typo (see edit history)

[Delboy52]

I've not seen that myself. Just did a search through the owners manual and the word "square" is never used for winter tyres. Just that all season tyres are adequate for winter conditions but winter tyres are much better suited in heavy or loose snow.

[Sheefa]

I ran 295/40/18 tyres on my old Supra, CCW wheels, with no need to roll arches. All depends on offset of course.

 

 

[Kaamos]

I've not seen that myself. Just did a search through the owners manual and the word "square" is never used for winter tyres. Just that all season tyres are adequate for winter conditions but winter tyres are much better suited in heavy or loose snow.

 

user manual, page 145 : "If you need snow tires, select the 235/45zr17 snow tires on your toyota" without mentioning front or rear so I assume they mean same size all around.

[Kaamos]

sheefa, that's interesting knowing at last that 295/40/18 in the rear, if they do 295/30/18 sure will (again, depending on offset).

 

But then I doubt 265 would fit on the front so it would be 295 rear 235 front..... would that be "balanced", grip-wise or would you people rather go for 255 rear/235 front ?

[Sheefa]

I had 265s on the front too, no arches cut or rolled with the CCWs.