Rear Wheel Width?

madmetcalfe69 · Jun 1, 2016

Hi,

I've just replaced my rear wheel (2001 K1 GSXR1000) with one that was advertised as from a 1000cc K3. I'm suspecting its actually from a 750 or 600 as the tyre profile is now sharper.

To make sure, can anyone tell me the external measurement of the 1000cc rims? I know they are 6 inch but presumably measured internally where the tyre beads. Can someone measure the external dimension lip to lip so I can measure without removing the tyre?

Oh, and hi everyone, ride safe dudes.

BillV · Jun 2, 2016

My OEM K6 wheel measures 6.885" to the outside of the lips and somewhere around 6.382" to the outside of the rim faces (they seemed to have a slight taper). So it looks like the aluminum wall thickness is around .2". A K1 wheel may be a little bit different but, as they both are 17 M/C × MT 6.00, it shouldn't be by much.

Anthony D · Jun 2, 2016

Isn't the rim size stamped on the wheel? Can't you tell by that? One will say 17 x 6, the other will say 17 x 5.5.

madmetcalfe69 · Jun 2, 2016

Cheers both, seems my ebay seller was a little frugal with the truth. it is indeed a 5.5" rim. need to either get a 6" rim or a 180 tyre. Cheers guys.

Anthony D · Jun 2, 2016

You will need different spacers I believe if you try to use a 5.5" wheel on a 1000 s/a.

madmetcalfe69 · Jun 3, 2016

It came with an axle and spacers and its fitted fine so not an issue. I didn't notice any difference in the spacers though to be honest.

I've fitted it with a 190/55 and just read up on it a little, I think it'll be fine to just run this tyre until the next change. Thought something was up as I normally use all the tyre to the edge but this still has 10mm chicken strip. Apparently if you're valentino rossi the sharper angle comes in handy as the motogp boys run the equivalent of 190/60 on 5.5" rims. I'm just going to have to either find a racetrack (and some skill) or look like a baby for the next 3000 miles.

BillV · Jun 3, 2016

Running a bigger tire on a smaller width wheel sounds counterintuitive. I'd think that the superbike racers would be a better guide. Check what the tire mfr. recommends. But beyond that, if you're happy, go with it.

Anthony D · Jun 3, 2016

MotoGP run a 17x6.25" rear wheel with a 190/650 rear tire.

Giorgio_Rp · Jun 3, 2016

Not good. You'll have limited contact patch at steep lean angles. Change the rim or the tire.

madmetcalfe69 · Jun 3, 2016

Definitely seems the other way around IMO. It has a bigger contact patch at steep lean angles as the tyre is slightly flatter profile near the edge (sharper profile in the middle). I do ride pretty hard and it seems way more stable at full lean AND more willing to tip in.

Not saying its ideal but the benefits seem to be outweighing any negatives for me.

Will let you know if it all goes pear shaped and I bin it, you can have a free 'told you so' on me

Anthony D · Jun 3, 2016

The 190/55 on a 5.5" rim will make the bike turn in easier, but make side-to-side transitions much more difficult. Yes, you will have some added contact patch while leaned over, but it won't be noticeable unless you are on the track turning hot laps.

180/55 on a 5.5" rim
190/55 on a 6.0" rim

tatersalad314 · Jun 4, 2016

I'm running a 190/55 Q3s on a 5.5 right now with one track day in. The only difference I notice is a better turn in but less power transfer with stock gearing. Ilthe benefits will only be noticeable on the track if you're surpassing the abilities on a 180.

GSXR Maori · Jun 5, 2016

190/55 will work. My mate used to run that on his 600. He uses a 180/60 on a 5.5 rim in his classic class. The 750 rim will fit straight in to the 1000, but not the K6 onwards 600/750 rear rim.

Giorgio_Rp · Jun 7, 2016

It could be different from tire to tire but theory says that using 190 section tire on a 5.5" rim gives less contact patch at the edges because they (the edges) become too steep to give usable contact patch. iirc Lee Parks mentions it too in his book.

Rear Wheel Width?

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