Was just strongly discouraged from getting 245 tyres on the back

[Cornwall1888]

Just been to Costco to get rear tyres fitted, I ordered 245/40/18 because they are cheaper, fill tyre gap more and decrease under steer.

I knew they weren’t the standard size but I use for my winter tyres

The fitter phoned me and said I ordered the wrong size, I told him i was happy with them, he initially refused to fit them then said he would if I signed a waiver because it could make my insurance invalid.

In the end I said if the 255 are in stock just put those on, cost me another £40

Should I have stuck with 245 or not worth the hassle? he said forum advice is all well and good but they do t insure your car

 

[TheDan]

Pretty certain they are chatting I am afraid. If you want to make sure then ring your insurers and ask about fitting slightly different tyre sizes, but unless you are fitting slicks I have not heard of any insurers having issues with this.

I fitted 245s on the rear of mine but they were 245/35/18 so less of a circumference difference than your plan. When compared to the standard 255/35/18 size, 245/35/18 is about 1.1% smaller and 245/40/18 is about 2.8% larger.

I also had the fitter phone me (Protyre) and ask if I had ordered the wrong size as they were different from what was coming off. I told him no I meant to order that size as it was cheaper and he was fine with this and fitted them.

 

[Zulu4]

I want to fit 245/40R18 too, for exactly the same reasons as you. It is your car to do with as you wish and not as the tyre fitter wishes. He should just fit the tyres you specify, and only advise if he has concerns.

I would have taken my custom elsewhere. I've noticed recently that National Tyres have become more competitive and are often lower in price than BlackCircles.

 

[grumps]

I've noticed recently that National Tyres have become more competitive and are often lower in price than BlackCircles.

I've just bought a pair of Goodyear Eagles for the front of mine and Halfords were a lot cheaper than anywhere else for the same tyre, albeit with their current 10% discount.

 

[mmm-five]

They're just covering their own arses in case you come back a week later to say they've supplied/fitted the wrong size.

They tell me the same whenever I ask them to fit 265s to the rear of mine. I just sign the waiver.

 

[Mr Tidy]

I'd have wanted them to fit what I asked for - it's not their car!

Luckily when I bought tyres for my Z4 last month I'd just had the wheels refurbed so I collected them in my daily which meant there was no argument about having 255/45 rears instead of the OE 255/40s.

A bit more sidewall for an older owner, and they fill the arches a bit more.

 

[Cornwall1888]

I ended up going with the 255 just to save any potential hassle with insurers, I’m sure it would’ve been fine but I didn’t want to be stuck with the “wrong size” then have to pay the same again and a bit more.

Michelin pilot sport 4 £240 for the rears instead of £203 for the 245

245 is actually the recommend size for an 8.5 wheel, 255 is a bit big, not sure why bmw chose the 255

If you look at the 225 on the front they are just right

Ah well

 

[Smartbear]

I ended up going with the 255 just to save any potential hassle with insurers, I’m sure it would’ve been fine but I didn’t want to be stuck with the “wrong size” then have to pay the same again and a bit more.

Michelin pilot sport 4 £240 for the rears instead of £203 for the 245

245 is actually the recommend size for an 8.5 wheel, 255 is a bit big, not sure why bmw chose the 255

If you look at the 225 on the front they are just right

Ah well

Aren’t the front wheels a narrower rim?
Rob

 

[Mr Tidy]

Cornwall1888 wrote: ↑Mon May 17, 2021 9:39 pm
I ended up going with the 255 just to save any potential hassle with insurers, I’m sure it would’ve been fine but I didn’t want to be stuck with the “wrong size” then have to pay the same again and a bit more.

Michelin pilot sport 4 £240 for the rears instead of £203 for the 245

245 is actually the recommend size for an 8.5 wheel, 255 is a bit big, not sure why bmw chose the 255

If you look at the 225 on the front they are just right

Ah well
Aren’t the front wheels a narrower rim?
Rob

Yes, fronts are 8J.

But 255 does seem wide for an 8.5J given that my M has 9J rears but the OE tyre width for that was also 255. :?

 

[TheDan]

245 is a much better fit and IMO means the car has a much more neutral balance instead of always understeery (of course some proper camber settings will affect that more). Btw here is a table for advised tyre widths based on wheel width: