M5 Tyre Sizes and Handling

1618 Views 9 Replies 6 Participants Last post by M540i LE, May 26, 2005

erikm54life

Discussion Starter · May 25, 2005 (Edited)

Hi guys!....just about to pick up my car and she's in dire need of new rubber.I was reading the M5 FAQ and a guy says that BF Goodrich tyres are the best he's used.Can't recall the particular make...think they're BFG g-force KD. My question is this i've found the same tyre set at a reasonable price...the snag is that the rears are 255/40 17 while the fronts are 205/50 17.....these 205's seem wider than most 205's i've seen....seems a lot of manufactures play about with exact specs!......if i go for this set-up will there be adverse negative effects?...Secondly we have a lot of roads that promote tramlining and really wide fronts will agravate this situation.....so my thinking was putting a narrower tyre up front to help this and also promote steering feel!

Remember,also that this BFG 205 is as wide as some 225's

:M5launch:

M5 1994 Nurburgring package.
E36 325i
E30 325i

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Mmm-Five

· #2 · May 25, 2005 (Edited)

If you are on original wheels then 205 width tyres will not cover your rims properly and will be very stretched. This means there will be less tyre roll, and even the chance of the tyre coming off the rim on hard cornering.

You will also create more understeer as the front will have proportionally less grip.

Personally I wouldn't* go less than 225 width.

* says the man doing a trackday next week with 205 front tyres on - purely to destroy them before fitting proper 225/245 F/R track tyres.

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farrell

· #3 · May 25, 2005

erikm54life said:
Hi guys!....just about to pick up my car and she's in dire need of new rubber.I was reading the M5 FAQ and a guy says that BF Goodrich tyres are the best he's used.Can't recall the particular make...think they're BFG g-force KD. My question is this i've found the same tyre set at a reasonable price...the snag is that the rears are 255/40 17 while the fronts are 205/50 17.....these 205's seem wider than most 205's i've seen....seems a lot of manufactures play about with exact specs!......if i go for this set-up will there be adverse negative effects?...Secondly we have a lot of roads that promote tramlining and really wide fronts will agravate this situation.....so my thinking was putting a narrower tyre up front to help this and also promote steering feel!

Remember,also that this BFG 205 is as wide as some 225's :M5launch:

M5 1994 Nurburgring package.
E36 325i
E30 325i

The front tyre size from the manufacturer for the 8 inch wide x 17 inch diameter is 235 x 45 x17

I hope you have mis-typed the 205 width that you mention.
Fitting this size of tyre to a rim that is already the same width as the tyre is not a recommended course of action. I doubt that you could successfully fit it any way if indeed it is a 205 width tyre.

The rolling circumference with also be wrong.

Regards
Farrell

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farrell

· #4 · May 25, 2005

Mmm-Five said:
If you are on original wheels then 205 width tyres will not cover your rims properly and will be very stretched. This means there will be less tyre roll, and even the chance of the tyre coming off the rim on hard cornering.

You will also create more understeer as the front will have proportionally less grip.

Personally I wouldn't* go less than 225 width.

* says the man doing a trackday next week with 205 front tyres on - purely to destroy them before fitting proper 225/245 F/R track tyres.

Mmm-Five
Are the 205 tyres a track or road tyre ?
The reason I ask is that the 5 series is a heavy vehicle.
The O/E has to ensure that the tyres maximum laden rating is not exceeded
or all warranty & responsibility by the tyre manufacturer is void.
The figures work on Gross vehicle weight divided by the number of tyres.
This can be optimised by weighing all four corners of the vehicle & working out the distribution of weight front to rear.

The bottom line is a car that weighs a couple of thousand kilos with fuel & a passenger alone is going to far exceed the max load rating for a 205 road tyre by such a margin that I would be very nervous of using it personally.

Regards
Farrell

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Mmm-Five

· #5 · May 25, 2005

farrell said:
Mmm-Five
Are the 205 tyres a track or road tyre ?
The reason I ask is that the 5 series is a heavy vehicle.
The O/E has to ensure that the tyres maximum laden rating is not exceeded
or all warranty & responsibility by the tyre manufacturer is void.
The figures work on Gross vehicle weight divided by the number of tyres.
This can be optimised by weighing all four corners of the vehicle & working out the distribution of weight front to rear.

The bottom line is a car that weighs a couple of thousand kilos with fuel & a passenger alone is going to far exceed the max load rating for a 205 road tyre by such a margin that I would be very nervous of using it personally.

Regards
Farrell

It's a road tyre that came on a set of wheels I bought for track use. I don't really want to put the P-Zero Corsa tyres on just to destroy them on an airfield event - I'd rather save them for a proper circuit.

I'll check the load rating this weekend, and as long as it is more than 93Y they should be fine - especially if Elvington is wet. I'm going to have a look at them this weekend and decide as I have a total of 7 part-worn P-Zero Corsa tyres in 225 and 245 widths (4x225 and 3x245) so I could put the 225's on in place of the 205's if they look really bad and still have a spare set for a proper circuit.

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IvanDias

· #6 · May 25, 2005 (Edited)

My rears are being replaced Saturday.

If anyone wants 2 Pirelli P-Zero Asymmetrico 265/40/17 that are on the wear bars, in order to go messing around on airports with, please tell me now otherwise they will be left with the tyre people.

The outside edge has about 3ish mm on, the inside is the legal minimum. I would not advocate any road use.

I already have my previous-to-these rears for track use so have no need of another two.

Shipping to anywhere on the UK mainland will be about £30-40 probably, given their weight and size, (maybe less???) or you can collect from Poole in Dorset.

Ivan.

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Mmm-Five

· #7 · May 25, 2005

IvanDias said:
My rears are being replaced Saturday.

If anyone wants 2 Pirelli P-Zero Asymmetrico 265/40/17 that are on the wear bars, in order to go messing around on airports with, please tell me now otherwise they will be left with the tyre people.

The outside edge has about 3ish mm on, the inside is the legal minimum. I would not advocate any road use.

I already have my previous-to-these rears for track use so have no need of another two.

Shipping to anywhere on the UK mainland will be about £30-40 probably, given their weight and size, (maybe less???) or you can collect from Poole in Dorset.

Ivan.

Thanks for the offer, I will let you know on Friday as I need to find out exactly what I've got on my track rims before I go taking advantage of your offer.

I'll have to ask the local tyre place what part-worns they've got, as I tend to replace my 18's quite regularly and I'm hoping someone with 17's does the same.

Then again I might just invest in some proper track rubber if I know I can do 4-6 events (non-airfield) on them.

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Sebas

· #8 · May 25, 2005

Hello,

Im running the new BF Goodrich G-Profiler and they are excellent. Dry or Wet. The patern for the front ones (235-45-17) is diferent for the rear ones (255-40-17). I would not recomend anything smaller than 235.
Best Regards
Sebastian
M5 Touring Daytona Violet

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Mmm-Five

· #9 · May 25, 2005 (Edited)

I know the narrowest tyres on the e34 were 205's (on 15" rims) but I assume these were on the smaller (& lighter) engined cars such as the 518, 520 & 525 - and 225's (16" rims) were used on some of the larger engined e34s.

I'm not planning on using 205's all the time, just for the one track day to have lots of wheel-spinning and hooning fun without worrying about damaging my road or track (17" Pirelli P-Zero Corse) tyres.

For all I know they may only last 20 minutes, but at least it will be a good 20 minutes. My normal road tyres would only last a day and they cost £600 to replace - these tyres were free with the wheels and they only cost £300.

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M540i LE

· #10 · May 26, 2005

Ivan

How did you find the Assimetricos?

After much deliberation, I have elected to go for P Zero Rosso Assimetricos all around and would be interested in your experience.

Cheers

IvanDias said:
My rears are being replaced Saturday.

If anyone wants 2 Pirelli P-Zero Asymmetrico 265/40/17 that are on the wear bars, in order to go messing around on airports with, please tell me now otherwise they will be left with the tyre people.

The outside edge has about 3ish mm on, the inside is the legal minimum. I would not advocate any road use.

I already have my previous-to-these rears for track use so have no need of another two.

Shipping to anywhere on the UK mainland will be about £30-40 probably, given their weight and size, (maybe less???) or you can collect from Poole in Dorset.

Ivan.

Save

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