Front tyre size ?

[Fenick]

just about to change my front tyre on the s1000rr, its got a 120/70/17 on there at the mo, but i saw one the other day with a 120/60/17 on it, whats best? any thoughts ? (already got a pirelli diablo rosso 2 190/50ZR17 ready to go on the back) , cheers in advance

 

[Parley Waller]

just about to change my front tyre on the s1000rr, its got a 120/70/17 on there at the mo, but i saw one the other day with a 120/60/17 on it, whats best? any thoughts ? (already got a pirelli diablo rosso 2 190/50ZR17 ready to go on the back) , cheers in advance

I would stick to what is recommended , BM don't spend big bucks on tyre spec for no reason - see you are going for non standard size on the back as well !!
If you are using the bike for road use and you have an off your insurance may frown if they are sharp enough to pick up on the non standard sizes ? But I may well be wrong.

 

[Cavey]

hey Fenick.....may also be worth noting that the bike's electronics (particularly traction control) could well react differently if you change from the recommended tyre sizes?? It will no doubt still work, but the electronics will intervene at a different stage.....not quite sure if this will compromise safety or not but personally i'd rather stick to the spec that BMW have designed the bike around. Does anyone know of any advantage of changing tyre sizes and if my concerns are valid?

 

[yam-andy]

what is your reasoning behind going down in profile size? most people tend to go up?!

 

[fast_ryan]

Tyre Sizes

It's not unheard of to change tyre profiles to suit different circuits when racing and using slicks, unless you are on a control tyre, but even then the options available are limited. That said its normally only the rear tyre that gets changed as front tyres are generally always a standard 120/70 profile. The trade-off is normally between turn-in speed and increased contact patch at high lean angle at the cost of stability. DTC can be adversely affected when changing profile sizes as the parameters need to be altered in the software to take into account the differing variations in tyre height and diameter. Hence why most racers will be using the HP Race Calibration Kit and/or will likely change suspension geometry to suit the tyre as well.

 

[Fenick]

what is your reasoning behind going down in profile size? most people tend to go up?!

hmmm , i bought a new 190/50/17 as that what was the size that was on there :/ , should have checked sizes i spose. .. having said that tho i did ride it down to LeMans this year at slightly mental speeds with no ill affects to the handling . , will have to sort out the correct sizes next time round ...
Has anyone else used these 'smaller' sizes ?

 

[mibridger]

I think you will find that bikes with the option forged wheels have the 200 section tyre, while the ones with the standard wheels have the 190 rear fitted as standard.

The bike is coded at the factory to the size that was fitted.

Having said that, mine had the 200 section tyre with the forged wheels and I have fitted 190 section slicks for the track with no ill effect.

I measured the tyre widths and they were within 5mm.

The DTC has a 10% 'wriggle factor' so you should be fine.

 

[Flatstick]

Have fitted a 180/60 on mine and not noticed any real difference, all electrics seam to work as per the 190.
The reason for change is that I can a set of them of a local British super sport team for ?75 and have done only a few laps.
I ran 180 on my Gsxr 1000 for ten years with no probs but will ask the motorrad people at the bmw track day on the 29th.

Dean