# Low Profile Tyres



## kfpg (21 Aug 2006)

Can any car experts tell me why it seems like my new car gives an unusual drive. I have gone from a 318i with regular tyres to a 318d with low profile tyres.
The car seems to 'pull' all over the road and it really is not a nice drive. All I can think is that it is the effect of the low profile tyres and their wider contact surface with the road. A friend confirmed to me that it is his experience that low profile tyres do give a strange feel to the drive.

Can they be changed easily to regular tyres, would the alloy itself need to change along with the tyres, OR maybe my problem has nothing to do with this???


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## RonanC (21 Aug 2006)

have the wheels and tyres been balanced? Is your tracking ok?? what about camber ??? all these will affect the driving feel from wheels


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## kfpg (21 Aug 2006)

Thanks Ronan that is the first thing I did i.e. fully balanced, tracked and camber adjusted. It made no difference.


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## Eurofan (21 Aug 2006)

You are probably experiencing tramlining, see [broken link removed] for a brief explanation. Larger wheels in combination with lower profile tyres have a number of effects, while they can be more aesthetically pleasing and improve cornering and handling they also reduce the ride comfort and have a diminished ability to handle rough surfaces and potholes.

It'd also be worth checking your tyre pressures. While debate can vary on what you should be running i've found 30/32 or 32/34(front/rear) to be an adequate compromise.


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## kfpg (21 Aug 2006)

Eurofan - thanks - "Tramlining" I would say that is exactly what is happening especially noticable on secondary roads where there is wear from heavy trucks and general poor maintenance of the road.

Does anyone know if I can just change the tyres or does the alloy need to change also. I really don;t like this tramlining sensation!


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## smcgiff (21 Aug 2006)

Lakeview said:


> Does anyone know if I can just change the tyres or does the alloy need to change also. I really don;t like this tramlining sensation!


 
Nope, you don't have to change the alloys. Go to any tyre "shop" and they'll have you back on the road in 10 mins.


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## Leo (21 Aug 2006)

If you change the profile, i.e. depth of the tire, you will also have to change the rims in order to preserver the outer diameter.


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## Eurofan (21 Aug 2006)

smcgiff said:


> Nope, you don't have to change the alloys. Go to any tyre "shop" and they'll have you back on the road in 10 mins.



The above is incorrect, Leo is bang on. Changing the profile without changing the size of the alloy will completely throw out the diameter of the overall tyre/wheel and will have other implications including underreading on your speedo.

You shouldn't experience this upto about 16" alloys with 50 or 55 sidewall. I currently have 17"s on my own car with a 45 sidewall and tramlining is present but not too bad. 18" alloys or above can experience bad tramlining depending on the kind of roads you tend to drive on.

I would emphasize checking your tire pressures though, it's amazing what a difference this can make.


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## smcgiff (22 Aug 2006)

Lakeview,

Check with your garage. Chances are they wont recommend a change in alloys - You can get 17" alloys with 55m depth.


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## Eurofan (22 Aug 2006)

smcgiff said:


> Lakeview,
> 
> Check with your garage. Chances are they wont recommend a change in alloys - You can get 17" alloys with 55m depth.



With all due respect please stop misguiding the chap. The information you are providing is way off the mark and shows a profound lack of understanding of how tyres/wheel combinations work.

While you can get 17" alloys with 55m depth that is not a correct size for bmws. I am currently running 17" with tyre size 245/45/17. In order to get a 55mm sidewall you'd have to reduce the width of the tyre to 185 in order to maintain the correct rolling diameter overall (absolutely vital).

He hasn't mentioned what size alloys he's using but i suspect they are 17" minimum. He could get away with 205/50/17s which would help but if he's finding the tramlining to be that disconcerting (and some people do) he's much better off dropping to 16" or even 15"s.


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## smcgiff (23 Aug 2006)

Eurofan,

I've advised him to get advice from a garage and not an anonymous poster.

You've recommended he gets new alloys. If he gets BMW alloys he's going to pay well over a thousand euro. If he doesn't go with BMW alloys he's going to lose €€€ in trade in value. He definitely should seek advice from a garage before making such a decision.


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## smcgiff (23 Aug 2006)

Eurofan said:


> He hasn't mentioned what size alloys he's using but i suspect they are 17" minimum.


 
The Standard alloy (according to BMW's website) for the 318d is 16" and the standard tyre is 205/55 R16.

There was no mention of larger wheels, but presumably they would be available.


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## Eurofan (23 Aug 2006)

You advised him he wouldn't have to change alloys, i (and others) pointed out you can't just arbitrarily change profile without affecting rolling diameter.

If he's downsizing alloys then he will have a set to sell and will not have to pay a fraction of what you suggest, there's always a willing market for 17"s and above on the various bmw boards and the bmw Ireland Club.

He specifically said originally he was running low profiles (but neglected to say what size alloys), that's not going to be 16" with a 55 sidewall but would be a good size to move to.

As for 'anonymous' advice on the internet a/you're the only one providing incorrect info and b/it is, at least, without bias which you cannot guarantee from a garage with something to sell to him.

I can heartily recommend www.bmw-driver.net and www.bmwcarclubireland.com for further advice along these lines along with options (if you so choose Lakeview) for disposing of whatever alloys you may have if you decide to downsize.


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## Dave T (23 Aug 2006)

Hi ,


I work for a vehicle importer at technical level and if I had a euro for every time Ive seen this Id be retired today.

Firstly some backround questions ....

Are the alloys & tyres on your new car a factory factory fit?
If not what was fitted (alloy?,rim & tyre size pls)?

Were the tyres & wheels on your old beamer a factory fit? (alloy?,rim & tyre size)

Sorry for the questions , but its impossible to answer without these vital items of info. 
Put very simply choosing wheels & tyres is all about compromise and achiveing an acceptable balance ie. road holding VS vehicle comfort/ride. Manufactures spend millions in the design/field testing in order to get the perfect wheel/tyre/suspension compromise or combination.
If youve fitted a wheel or tyre outside of spec youve have probably undone all that the manufacturer intended you to have with regards to road holdoing & comfort.

Dave


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## smcgiff (23 Aug 2006)

Eurofan said:


> “If he's downsizing alloys”


 

There’s no suggestion that he is. 

If he has standard 16” alloys then the previous car could have had lower profile tyres, such as 45. He wouldn’t need to change alloys to put on 55m tyres. They would in fact be standard. 

Is my above comment correct or not?



Eurofan said:


> As for 'anonymous' advice on the internet a/you're the only one providing incorrect info and b/it is, at least, without bias which you cannot guarantee from a garage with something to sell to him.




This from someone who, in another thread, advised someone to conduct themselves in a manner that would void their insurance cover. And, now, you’re advising someone to take anonymous advice over that of a garage. Next you’ll be advising on the wearing of tinfoil hats when taking a car in for a service.


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## Leo (23 Aug 2006)

smcgiff said:
			
		

> If he has standard 16” alloys then the previous car could have had lower profile tyres, such as 45. He wouldn’t need to change alloys to put on 55m tyres. They would in fact be standard.
> 
> Is my above comment correct or not?


 
No, you cannot just change the tire from a low profile to a 55mil without changing the rim diameter by the corresponding amount. The combined diameter of rim and tyre must remain constant. 

Otherwise speedo readings will be rendered inacurate, and the ratio of wheel turns to drive shaft revolutions will change, throwing out the gearing ratios BMW presumably spent some time tuning.


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## smcgiff (23 Aug 2006)

http://www.michelinman.com/specs/pilot_mxm4/112.html

Leo,

From the above website you can get, say, 225/55R17 & 225/45R17.

The only difference I can see is that the tyre depth changes from 45 to 55. Would these tyres fit a 17” alloy


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## HighFlier (23 Aug 2006)

There has been a fair bit of confusion going on in relation to this.

The facts are as follows.

1. Car manufacturers fit a wheel/tyre combination to give a certain fixed finished wheel diameter. The gears and speedometer and even such basic things as wheel clearances are calculated using this fixed figure.

2. Any subsequent changes must reflect this and the wheel/tyre combination must maintain the same overall diameter.

3. Tyres have three dimensional statistics width ,depth and wheel rim diameter.

A 225/55R17 is a tyre which has a tread width of 225mm an "aspect ratio" of 55% (i.e. the sidewall height is 55% of the tread width. "R" means it's a radial ply tyre and 17 is the diameter in inches of the hole in the middle which defines the appropriate rim.
So if you change the rim diameter calculate the required change in tyre wall height to suit and the closest fit is the correct tyre to use


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## redo (23 Aug 2006)

http://www.alloywheels.com/tyrecalc.asp

http://www.alloywheels.com/fitment.asp?psearch=BMW


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## smcgiff (23 Aug 2006)

HighFlier said:


> So if you change the rim diameter calculate the required change in tyre wall height to suit and the closest fit is the correct tyre to use


 
But what if you don't want to change the rim diameter?


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## HighFlier (23 Aug 2006)

Then if you change the tyre profile you put up with an incorrect speedo, wrong gearing and possible safety and insurance issues. Larger rims are fitted by people who want low profile tyres for performance purposes and are not suitable for higher profile tyres of the same diameter. But there's plenty people who will sell and fit them for you if you like.


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## smcgiff (23 Aug 2006)

redo said:


> http://www.alloywheels.com/tyrecalc.asp


 
Handy website - Going by the first website it looks like I could go from my 45 to 35 % depth and keep my same alloys. Good to know!


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## smcgiff (23 Aug 2006)

HighFlier said:


> But there's plenty people who will sell and fit them for you if you like.


 
But would, say, Michelin manufacture a tyre configuration/ratio that was dodgy?


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## HighFlier (23 Aug 2006)

If you look at the website linked it actually calculates for you how much inaccuraccy you are building in to your speedo. Its simple mathematics and there is a right size. The smaller the deviation the smaller the problem for sure but I look at some of the monstrosities on the road and somebody sold and fitted tyres which are blatantly incorrect on these vehicles.

The owners manual will list the suitable tyre/ rim combinations and if you calculate the "Effective finished wheel diameter" you will see they are all in a fairly narrow range with rim diameters compensating for profile changes. 

1 + 1 must equal 2 at some stage.


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## smcgiff (23 Aug 2006)

HighFlier said:


> The owners manual will list the suitable tyre/ rim combinations and if you calculate the "Effective finished wheel diameter" you will see they are all in a fairly narrow range with rim diameters compensating for profile changes.


 
Good point!


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## kfpg (23 Aug 2006)

Lads - I must say I am very impressed ye have had a 2 page discussion on my post - sorry I wasn't around to contribute until now. For the record my tyres are 

225 45R 17 91V (Bridgestone) - note they are Run Flat tyres !!

alloys are Star Spoke 158 8J x 17

I need to re-read everyone's comments again - but I think it looks like I could go for a 16 alloy and a suitably matched tyre to maintain total wheel diameter. It seems other tyre sizes with the same alloy seem to create problems unless I misread.

A final point is that although the issue is what is known as 'tramlining' part of the less than ideal drive quality is also the hardness of run flat tyres which BMW have unfortunatley implemented.

Thanks to everyone!!


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## Eurofan (24 Aug 2006)

Lakeview said:


> A final point is that although the issue is what is known as 'tramlining' part of the less than ideal drive quality is also the hardness of run flat tyres which BMW have unfortunatley implemented.



Ah thats a new development and not an uncommon problem, i know of three people who had run-flats issued as standard and quickly replaced them due to the problems you described and a very harsh ride quality.

You _may_ not have to downsize in this case. I'm also running 17" with exactly the same tyre size but not run-flats. I also drive a 3-series but it's the last generation (E46) not the current model.

Have a look around the bmw boards i mentioned and you'll be able to solicit more advice on the matter. I'm not sure if your local tyre shop would accomadate 'trying out' non-run-flats before deciding to downsize to 16" alloys but if not i can recommend a good tyre place on the Northside who would possibly do so as a favour (I'll ask tomorrow).

Also if you do decide to go down the road of switching alloys sizes 16" are more commonly available second hand (again on the forums) and 17" should sell on quite easily.


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## kfpg (24 Aug 2006)

Thanks Eurofan - I would love to go to non run flats and carry a spare BUT !! the boot design does not accommodate a spare anymore in the 2005 model. I think the whole thing is stupid and this may be my 3rd and last BMW.


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## Eurofan (25 Aug 2006)

It's quite some time since i've carried a spare as well to be honest, it's bucketing down at the moment so i can't go out and check the name of it but i always carry two cans of tyre sealant which is a darn site quicker and less messy than changing a wheel. No need to worry about the spare.


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