Sorry, Tyres?

[msherry21]

Hi all, Once again I have another query:

Whats the perfect size tyre for the following 17" wheels?

7J - Front?

8J - Rear?

I have at the moment (because TRD said so)

Front - 215 45 17

Rear - 235 40 17

any opinions on this?

Cheers,

Michael.

[Jimlad]

most people normally go for

215/40/17 front

235/40/17 rear

[Jesus]

I'm running 17 x 7J fronts with 215/40/17, and 17 x 8J rears with 235/40/17.

They match the stock circumference pretty well.

I think you'll find that's the most popular tyre sizes people use.

[Bibbs]

I'll be running

215/40/17 on a 7J and 235/35/18 on a 7.5J

[msherry21]

yeah, thats what I had previously, TRD advised of this size, so I went for it. Proving to be excellent so far! better ride comfort and handling! will know more when I get time to drive it properly.

cheers for the info guys.

Michael.

[jaxx]

whats the recommended pressures aswell for these sizes? :)

[Jesus]

I'll be running

215/40/17 on a 7J and 235/35/18 on a 7.5J

←

That's what I'll be going with on my new set... although my rears are 18 x 8J.

[Jimlad]

whats the recommended pressures aswell for these sizes? :)

←

that's what I've always wondered too !!

My very nice local garage fitted my new tyres etc... but when they asked what pressure did I want.....

I didn't know what to say!! They then just done what they said was normal, can't remember now.... but would appreciate any advice on what they should be.

BTW ... I have 17*8J wheels alround

[jaxx]

mine i believe are at 30 and 32 psi....

wether thats right or not i dont know! tyre shop had that on the list so went with it

[Jimlad]

think mine are something like 29 and 28 ... dunno what is front or rear tho !

[jaxx]

bigger pressure in the back...

[Jimlad]

still dunno what it's supposed to be tho. Never noticed any issues with what my tyres are set to at the mo.

[c_master]

Mine are brand new on my wheels and not fitted yet, so as soon as i fit them i'll take em to sainsbury's and see what the pressure reads. See what the wheel place did them too. Not that this is necessarily correct. But will add greater scope

[Jesus]

Don't trust the gauges on the petrol station air compressors.

Get yourself a proper gauge. They're only a few quid. My mate pumped his tyres to 32 psi... so he thought. Checked with proper tyre gauge and it read about 36psi. Went back to the petrol station to test it again, and it still read ~32psi. They're not really accurate.

Tyre pressures can make such a difference to how the car behaves...

[GiJoe90]

I always thought it was 30psi at the front and 32psi at the rear. Can't remember where I read that tho!!

Joe

[Ryan1985]

I've got 30psi all round, my mate who is a tyre fitter said that is the norm, I have a Yaris though so it could differ!

[boundsw]

I run 1.8 bar fronts

2.0 bar rears.

just because on the inside of my door, there is some writting in japanese, and boxes below, one says 1.8, the other box 2.0, so i guess they are tyre pressures in bar (not psi)

and i guessed more pressure at the back ??

(2.0 bar = ~30 psi)

[Tyretech76]

I'll be running

215/40/17 on a 7J and 235/35/18 on a 7.5J

←

any doubts about tyre sizes, check with a reputable fitter. check the standards set by European Tyre and Rims Technical Organisation. They set the standards to which the tyre industry work to. For example, a 7.5j rear rim is not suited to the size 235/35 R18. That size shouldn't actually be fitted to a rim smaller than 18x8.

It's always best to get tyre sizes checked by experts.

[dj_davo]

im running 215/40/17 front and 245/40/17 rear on wide wheels. 8j front, 9j rear.

standard tyre pressures 15" are 29 front, 33 rear and the rule of thumb i have often heard is that for every 1 inch you go up in size - add 2psi, so a 17" over a 15" you would be adding 4psi extra - so 33 / 37.

a wheel specialist i know however said he had never heard of this rule and generally stays with the standard pressures and keeps an eye on the tyres over a few months for wear patterns.

if tyres start wearing on the outside - inflate more. if they are wearing in the middle - deflate more.

i've gone in between and am using 31 / 35.

[Stef Derner]

The tyre pressure is dependent on the weight of the car and the footprint of the tyre. To keep the car supported and maintain the shape and integrity of the tyre, the tyre pressure will vary if you change the weight or the tyre size. Unless you are going to double the width of the tyre or half the weight of the car, you shouldn't need to vary the pressure from stock. Adding 10mm to the width of the tyre will only vary the pressure by fractions of a percent, and not worth bothering with.