different profile tyres front and rear

colino

What is the point in posting the percentage aspect ratio and the tyre diameter without the tread width? That gives absolutely no information as to the actual rolling diameter of the road wheel.
Drivel.

Iceweasel

neilmcl wrote: »

Well my manufacturer tyre ratio recommendations are 40 (front) and 35 (rear) on 18s but they also state I can fit a 40 ratio 18" tyre all round or between a 45 and 50 ratio on 17s.

So again, it doesn't make that much of a difference nor will it make the car unsafe or handle abnormally.

That's fine - your car manufacturer recommends those variants.

Similar to mine - that 35 on the rear will be a wider tyre though.

But I'm sure that they don't recommend a 40 profile on the front and a 45 profile on the rear when you have 18" wheels all round.

From the OP's posts only the 40 profile is recommended on his car.

londonTiger

Iceweasel wrote: »

I can't agree with the several posters who say the difference is tiny and it will make little or no odds.

The car will NOT handle the way the manufacturer designed it to.

If all 4 tyres were oversized that just might retain the correct balance between front and rear.

The 45 profile tyres have higher sidewalls than 40 profile tyres therefore have more flexibility and the rear of the car will have more lateral movement.

For 95% of drivers for 95% of the time there will be no discernible difference but ....

I don't want to begin a big debate concerning Nuns with baskets of kittens, but it's in an unexpected swift/emergency manoeuvre that the discrepancy will show itself.

Taking a corner at high speed in the wet (which would normally be perfectly safe) could well turn out to be 'interesting'.

So much tripe, most cars are driven by 1 axle only- and you're talking about tiny increase in threadwall height causing catastropic difference in handling.

Next you'll be saying if on one axle on tyre is manfactured in 2010 and the other is manufactured in 2011 it should be changed and is a danger to the public.

Spicy_McHaggis

londonTiger wrote: »

So much tripe, most cars are driven by 1 axle only- and you're talking about tiny increase in threadwall height causing catastropic difference in handling.

Next you'll be saying if on one axle on tyre is manfactured in 2010 and the other is manufactured in 2011 it should be changed and is a danger to the public.

But then four different sized wheels would be safer than anything you've worked on.

JustinR1979

Spicy_McHaggis wrote: »

But then four different sized wheels would be safer than anything you've worked on.

Hopefully any car he has worked on has no wheels.

ratrace

neilmcl wrote: »

A lot of cars can accommodate multiple tyre sizes as options including different tyre ratios between front and back. A 5% difference in tyre ratio will have no ill affect.

Spot on!


My bmw m sport had wider tyres on the rear compared to the front that's how bmw made them I wouldn't worry about such a small difference

JustinR1979

ratrace wrote: »

Spot on!


My bmw m sport had wider tyres on the rear compared to the front that's how bmw made them I wouldn't worry about such a small difference

As did my M3 and M5, but this doesn't affect the rolling radius (which is in question) as the profiles were different


The only concern I would have is insurance wise, drivability etc I wouldn't give a second thought. Cars are developed on a certain tyre, 99% don't use this tyre; suspension will be worn/replaced, so may differences to when it rolled off the production line.

Iceweasel

londonTiger wrote: »

So much tripe, most cars are driven by 1 axle only- and you're talking about tiny increase in threadwall height causing catastropic difference in handling.

Next you'll be saying if on one axle on tyre is manfactured in 2010 and the other is manufactured in 2011 it should be changed and is a danger to the public.

That's good to know - so all these numbers on the side of a tyre can be ignored then.

I can't define a 'tiny increase' so any old tyre that fits the rim will do.

Seems that all the motor engineers and car designers are wasting their time.

pd52

I guess I going to have to shell out £170 on 2 tyres now. gutted

Iceweasel

pd52 wrote: »

I guess I going to have to shell out £170 on 2 tyres now. gutted

I'd be selling the tyres you take off on eBay or Gumtree

You may be surprised by what they are worth.

http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2055119.m570.l1313.TR0.TRC0.H0.Xbridgestone+205%2F45+17+tyres&_nkw=bridgestone+205%2F45+17+tyres&_sacat=0