16.5" wheels

**kerryg** · 3rd October 2005, 15:42

Was browsing and looking at MotoGP bike specs...as you do...and I noticed that they mostly run 16.5 inch wheels? What's with that? If 16.5'' is so good I woulda expected to see that size on the current hot sportbikes...and anyway where do you/can you even get 16.5" rubber , not that I want to, just curious

**F5 Dave** · 3rd October 2005, 16:30

Don’t start them -please!

16.5s came out ages back for racing slicks, but the tire & bike manufacturers obviously agreed that after the 18” to 16” then 17” fiasco of the 80s & trying to keep al those tires in stock in a myriad of widths, compounds & tread patterns -why the heck have 16.5s as well?

**k14** · 3rd October 2005, 16:32

Originally Posted by kerryg

Was browsing and looking at MotoGP bike specs...as you do...and I noticed that they mostly run 16.5 inch wheels? What's with that? If 16.5'' is so good I woulda expected to see that size on the current hot sportbikes...and anyway where do you/can you even get 16.5" rubber , not that I want to, just curious

Pretty sure you can't get road tyres/rims in 16.5". They do it because it reduces the rotational inertia of the wheels thus making it easier to turn. They made the change 2 or 3 years ago. It took them a while to be able to get the suspension etc sorted to cope with the change of geometry but I'm pretty sure all motogp bikes use them no. Not sure about 125's and 250's but I think they still use 17's.

Don't think it would be worth it on a road bike. Imagine how much extra tyres etc would have to be developed, along with all the extra development from the factories to get the bikes handling etc the way they do now.

**Two Smoker** · 3rd October 2005, 18:36

I think you might find that alot of the superbike guys are running 16.5 inch rims too...

**k14** · 3rd October 2005, 18:54

Originally Posted by Two Smoker

I think you might find that alot of the superbike guys are running 16.5 inch rims too...

Yeah thats right, I can remember stroud saying he had to buy a couple of sets of 16.5 inch rims for when he competed over in auzzie for the superbikes. Pretty sure that would mean that everyone runs 16.5's in supers cause they run a control tyre.

**Nutter34** · 4th October 2005, 02:49

The rolling diameter of the tyre is the same as a 17" is it not? What the 16,5" does, is for the tyre to more triangular, which results in the cornering section or angled part of the tyre to leave a larger footprint whilst leaned over, hence increasing grip... so I understand.....

**Motu** · 4th October 2005, 07:08

The important thing with these 1/2 sizes is not to get them mixed up with incorrect tyres.Of course the tyre is always marked with it's size,but the rim seldom is,at least not in big letters.We once fitted supplied tyres to some rims,for a small tractor thing,a plane hauler - standing around with a couple of other guys talking as the tyre fitter inflated the tyre,it blew off the rim and sent the rim 2 metres in the air,no one was hurt,but we were pretty freaked out.The tyres were 16in,but the rims were American 15.5in,not marked and also not the sort of thing you expect to come across,normaly you would take the original tyre off and see the size,but the rims and tyres were supplied seperatly.