Tire sizing...OEM size seems uncommon, what size to use?

[BigBill]

As the title states, the OEM rear tire size seems a bit uncommon so what is an acceptable alternate size, taking into account the affects on the MPG, speedometer, odometer and mileage calculations.

I see a lot of chatter about the inaccuracy of the NT's speedometer, etc...could it be the use of tires that differ in size to the OEM?

Its time for replacements so this is on my mind as I shop for new treads.

PS... I have seen a plug-in programmable speedometer/odometer error correction device for the NT.

 

[DirtFlier]

The speedo and odometer on my bike is accurate as I've compared it against what my GPS says and error, if any, seems to be less than 1%. The fuel mileage display is often wildly inaccurate but I never use it anyhow so it doesn't matter. In regards to the tire sizes, they are fairly common sizes for a bike this size.

 

[jackgermain]

Tires are very common. front 120/70 - 17
back 150/70 - 17
My speedo is dead on.

 

[junglejim]

The NT behaves pretty well with the OEM size tires. You could change the turn-in and and stability of the bike by messing around with different sizes, but I don't know why you'd want to. "If it ain't broke . . . ." What charicteristics are you looking for?

My speedometer is in good agreement with my GPS up to 70+ mph with OEM size tires.

 

[tawilke46]

My speedo is spot on with OEM size tires, Bill. Within 1mph or so of my GPS. Like others say, the avg mpg is reads 4 to 5mpg too optimistic.

 

[BigBill]

My OEM size on the rear is a 170/70zr17...have not seen that exact size in anything as of yet, though I did not bother to check for an exact model replacement as they seem to be of low quality and have no desire to use them again.

I should have specified its the REAR tire that is difficult to size exactly, the front is easy to match.

The NT behaves pretty well with the OEM size tires. You could change the turn-in and and stability of the bike by messing around with different sizes, but I don't know why you'd want to. "If it ain't broke . . . ." What charicteristics are you looking for?

My speedometer is in good agreement with my GPS up to 70+ mph with OEM size tires.

OK, now you just gave me a new factor...turn-in and stability...can you expand on that for this novice?

 

[Warren]

If you have a 170 on the rear it is not the stock OEM tire. Stock is a 150. Did you buy your NT used and are you sure it's a 170.

 

[BigBill]

Yes, its a 170, took it home from the dealer with that on it.

It did sit at the dealer for 2+ years, so its possible they robbed the original for an emergency repair elsewhere and replaced it with another they had in stock...who knows.

OK, the NT product page lists it as a 150/70zr17...that might help me find the right size.

 

[RedNigel]

The tire is easy to get online...just hard to find in a shop

 

[junglejim]

You'll like the handeling much better with a 150 instead of the 170 on there.

 

[Phil Tarman]

I'll jump on the bandwagon, too, Bill. If you had the OEM tire size, you'd have the most accurate speedometer I've had on any of the bikes I've had. Above 70 it reads a mile faster than I'm actually going. Over 1000 miles, there's been less than 3 miles difference from the GPS according to the odometer.

Your dealer must have swapped tires. If you get a 150/70 back on the rear, the handling will improve, your speedometer and odometer will be practically dead-on accurate and you'll get a little better acceleration (smaller tire is equivalent to a lower gear, IIRC).

 

[DirtFlier]

Having tires "in stock" with so many different bikes out there is a losing proposition for dealers which is why they usually have to order tires for a customer. And sometimes what they have in stock has been sitting there for years! Some of the accessory stores such as Iron Pony (OH) and Chaparrel (CA) carry a huge stock of tires but their internet order prices are cheaper so even there you can't have it both ways. And you can't order on the internet and pickup at the store so you're stuck with paying a bit more if you now the tires right now.