[SomeRandomer123]

Just wondering about the tyre pressures for this 116d EfficientDynamics I'm looking after. It has a set of 205/55/R16 91W on all corners, but this specification doesn't quite meet the tyre types on the door. The speed rating is different.

The closest type on the door is 205/55/R16 91Y, which says 2.8 in the front and 3.0 in the back.

So my question, do the different speed ratings affect the pressure I should inflate the tyres to? I don't think so, but it would just put my mind to rest to make sure.

Tah!

Oh and here is a quick phone camera photo for good measure!

[Fanis]

Originally Posted by SomeRandomer123

So my question, do the different speed ratings affect the pressure I should inflate the tyres to? I don't think so, but it would just put my mind to rest to make sure.

No, they do not affect the tyre pressure...as long as you have 205/55/16 tyres, go with the recommended pressure.

[Verglas]

Just bought some 245/45/17 part worn Bridgestone Runflats by mistake. Should have been 225/45/17. Anyone know if they will fit? Stu

[SomeRandomer123]

Originally Posted by Fanis

No, they do not affect the tyre pressure...as long as you have 205/55/16 tyres, go with the recommended pressure.

Cheers, I thought as much but couldn't be certain. I'll inflate happily now!

[Fanis]

Originally Posted by Verglas

Just bought some 245/45/17 part worn Bridgestone Runflats by mistake. Should have been 225/45/17. Anyone know if they will fit? Stu

OK, here are the facts:

1. BMW fits larger tyres at the rear (only), but they are 245/40/17 and not 245/45/17. Thus, the tyres you bought have a higher profile, making them larger in diameter. The difference is 2.84% and up to 3% variance is considered safe.

2. You wheels ar probably 7.5'' width, which is the min. width for this size but they fit. BMW uses wider wheels at rear (8'') and with higher offset (53 instead of 43, probably to keep the tyre within the fender and not stick out).

3. Since BMW does not fit 245 wide tyres at front wheels, I do not know if there is a problem with steering angle.

With all the above, personally I would try to sell the tyres and fit the proper size. However, if you choose to keep them, then try and see if they fit, especially at front wheels. If they fit OK without any rubbing and the steering wheel goes from lock to lock, then probably you will be OK, but make sure to notice any change of the car's road handling.

[Verglas]

Originally Posted by Fanis

OK, here are the facts:

1. BMW fits larger tyres at the rear (only), but they are 245/40/17 and not 245/45/17. Thus, the tyres you bought have a higher profile, making them larger in diameter. The difference is 2.84% and up to 3% variance is considered safe.

2. You wheels ar probably 7.5'' width, which is the min. width for this size but they fit. BMW uses wider wheels at rear (8'') and with higher offset (53 instead of 43, probably to keep the tyre within the fender and not stick out).

3. Since BMW does not fit 245 wide tyres at front wheels, I do not know if there is a problem with steering angle.

With all the above, personally I would try to sell the tyres and fit the proper size. However, if you choose to keep them, then try and see if they fit, especially at front wheels. If they fit OK without any rubbing and the steering wheel goes from lock to lock, then probably you will be OK, but make sure to notice any change of the car's road handling.

Thats great. Thanks for your time...Stu

[AndyLeng]

Hi there,

I'm after some advice please about tyre pressures for my 116ED. I have the stock fitted Michelin Energy Saver tyres fitted from new by BMW. They are 205 /55 R16 91W *.

Looking at the tyre placard on the drivers door it refers to two sets of tyres that don't match the factory fitted tyres specifically. They are:

205 /55 R16 91H M+S

with standard load being Front 2.3 (33.35 PSI) and Rear 2.5 (36.25 PSI)

or fully loaded; Front 2.5 (36.25 PSI) Rear 2.8 (40.61 PSI)


In addition there is another set of pressures for 205 /55 R16 91V:

for either standard or fully loaded as both being Front 2.8 (40.61 PSI) and Rear 3.0. (43 PSI)

Confusingly if I look on Michelin's website here and enter the tyre details it states the front should be 29 PSI and Rear 32 PSI!!! A quick look on Kwik-Fit and www.tyresafe.org states the same i.e. 29 PSI up front and 32 PSI on the rears!

As I'm sure you'll agree this is a considerable difference and I would like to know which to go for as the BMW placard doesn't match my specific tyres and there is a large difference in these tyre pressures which can affect handling. The BMW pressures seem pretty high which seems a little odd?

[ovekvam]

It is better to run too high pressures than too low, but there is no exact pressure that is correct for everybody. If I were you, I would go with 35 psi in all corners. Slightly higher with fully laden car.

[AusF20/F48]

Originally Posted by ovekvam

It is better to run too high pressures than too low, but there is no exact pressure that is correct for everybody. If I were you, I would go with 35 psi in all corners. Slightly higher with fully laden car.

I agree with ovekvam
Considering that most cars wheel/tyres used now are wider than they use to be, so it is better to have higher pressure to keep the tread flat which gives better wear and contact with the road.

[ttimbo]

Overinflation is a good rule of thumb but, like all things, best in moderation.

The manufacturer's placard is the most important piece of information, as it reflects what the vehicle's engineers have determined to be optimal inflation, taking everything into consideration (ride, handling, durability). The advice from the tyre manufacturer is instructive, but not the final word, as the tyres don't know what vehicle they've been fitted to.

In my experience, I have found that overinflation of my M135i's tyres (say, 40psi) actually makes steering/handling/ride worse, so I've dropped back to 34psi front, 36psi rear. Steering, in particular, is much better -- it gets too light if the fronts are >36psi.

That said, the placard information for AndyLeng's car, at 41/43psi, seems very high. My conclusion is that BMW regard the 116ED as being all about fuel efficiency, hence recommend high tyre pressures in pursuit of that goal. If you can bear the ride/handling at those pressures, then that's what I'd use.

[ovekvam]

Also, as a general rule, tyres with soft sidewalls require slightly higher pressures than tyres with stiff sidewalls, like runflats. The driving style matters as well. If you drive smoothly, you can go slightly lower on the pressures. For high speed driving in the rain, higher pressures are better.

BMW has always recommended higher pressures in the rear than the front. My experience is that the car handles better with equal pressures in all corners, but it depends on your driving style.

[HighlandPete]

Originally Posted by AndyLeng

..As I'm sure you'll agree this is a considerable difference and I would like to know which to go for as the BMW placard doesn't match my specific tyres and there is a large difference in these tyre pressures which can affect handling. The BMW pressures seem pretty high which seems a little odd?

You are comparing two different tyre types with the Winter M+S and the normal Energy Savers.

Your tyre is the same size and the same Load Index (key factor) as the one on the door placard, just a higher Speed Rating, so as close as you can get really.

I was surprised how high BMW run the ED model tyre pressures, 320d ED is the same, high pressures even for normal use. All part of getting the fuel economy.

HighlandPete