Changing tire profile

[BDO]

Can't find the tyre forum (although I am sure I have seen it before )so posting the question here - mods please move if I am wrong.

I have a Z4M Roady, and need to change the tires. The stock sizes are RIDICULOUSLY expensive (255/40/18 and 225/45/18), and the sales dude suggested that I go to 255/35/18 and 225/40/18. The price difference is about 60%.

I understand that the speedometer will over read by about 4%. The diameter difference is about 4% smaller too.

Will there be any other adverse effects (other than the speed overread)?

[RobertRO]

The shorter sidewall increases the risk of bending your rims when hitting potholes. Of course, this concern is valid only if the quality of the roads in your area is not so good.

[Shipkiller]

[BDO]

Originally Posted by Shipkiller

Cheers mate, that helped.

[prodigal_m]

[mshanno1]

Originally Posted by BDO

Can't find the tyre forum (although I am sure I have seen it before )so posting the question here - mods please move if I am wrong.

I have a Z4M Roady, and need to change the tires. The stock sizes are RIDICULOUSLY expensive (255/40/18 and 225/45/18), and the sales dude suggested that I go to 255/35/18 and 225/40/18. The price difference is about 60%.

I understand that the speedometer will over read by about 4%. The diameter difference is about 4% smaller too.

Will there be any other adverse effects (other than the speed overread)?

60% difference in price?? Are you comparing a Michelin to a Sumitomo?

[nmulax]

Ok… I'll bite.

1. Without knowing the price you were quoted there's no way to say if you were given a normal price or not. I don't think anyone on here would say tires are "ridiculously" expensive. Sure, they're pricier than rubber for a econobox, but it's a BMW, and an M. You go into ownership of a performance vehicle knowing some things cost more.

Are you looking at OEM replacements, or other brands of tires? Did you get pricing from your dealer (big mistake if you did)? A quick search of Tirerack.com shows stock size sets from $700-1,000. Obviously, you're outside the US, so I'm not sure what options you have for purchasing, but keep in mind tires are not the place to skimp on a 330+ hp machine.

2. The tire/wheel section is here.

[jophish17]

I wish I could have saved that much just by switching to a different ratio

Tire Rack is awesome - saves me 25% of what I was quoted by the local shop

[v3.2mc]

4% is a huge difference...

for every 1000 miles actually driven, your speedo will add 40. if you ever plan on selling the car, i wouldn't go more than 2%.

[Hawkeye]

nmulax, considering he typed tyre and not tire, I am guessing he is not US based.

I cannot help with prices outside the US, but I know switching from 18" to 15" in the US will not even save you 60% with similarly spec'd tires.

[nmulax]

Haha, yeah it was the "tyre" and "cheers mate"… nobody in the US says that

[BDO]

Originally Posted by nmulax

Haha, yeah it was the "tyre" and "cheers mate"… nobody in the US says that

LOL, eventually you guys will learn English too.

Managed to find some reasonably priced rubber in the right sizes, so crisis averted. Continentals, I much prefer Toyo (as well as the price difference), but hey.

Thanks again.

[Daemonblitz]

If your tire dude is recommending for you do do that profile switch I would drop him immediately.

Why don't you get yourself a nice set of Hankook V12s like you have on your 335 ?