[Panici]

New-to-me track bike came with a set of 190/650-17 and 120/600-17 slick tires. How do these sizes compare to the standard road spec sizes of 180/55-17 and 120/60-17 (or even 120/70-17 on newer models)? What are the equivalent tires in regular DOT measurements?

 

[Cipher_R6]

Keep in mind id never really heard of these tire sizes before seeing this thread. However I found some sizing info online for a set of Bridgestones. I compared that versus the standard sizes I’m used to seeing using 180/60-R17 vs 190/55-R17 Tire Comparison - Tire Size Calculator | Tacoma World

Assuming it’s all accurate, this is what I have.

For the rear, a Bridgestone (v01 or something) with the same 190/650 designation.

190/650-17
OD 649mm
TW 188.

180/55-17:
OD 630mm
TW 180mm

180/60-17:
OD 648mm ✅
TW 180mm

190/55-17:
OD 641mm
TW 190mm ✅

It’s kind of a mixture it seems. Personally I like the 180/60, it’s a taller profile and has good turn in responsiveness, also increased contact patch at the same lean angle versus 180/55.

On the front, again another Bridgestone 120/600 for comparison.

120/600-17:
OD 603mm
TW 117mm

120/60-17:
OD 576mm
TW 120mm ✅

120/70-17:
OD 600mm ✅
TW 120mm ✅

It seems to line up with the 120/70 size.

I hope this helps man. Again, this is based on specs I found online which could vary somewhat but hopefully puts you in the ballpark.

 

[Panici]

Keep in mind id never really heard of these tire sizes before seeing this thread. However I found some sizing info online for a set of Bridgestones. I compared that versus the standard sizes I’m used to seeing using 180/60-R17 vs 190/55-R17 Tire Comparison - Tire Size Calculator | Tacoma World

From what I can tell, (Toyota) Tacoma World is referring to car (truck) tires on that site.
I don't think those measurements will translate directly to motorcycle tires.

Where did you find the measurements for the race-sized Bridgestones? I'd like to bookmark the reference.
-

Also, the other thing that I came across this morning while doing some research was tire profile.
How quickly the tire "slopes off" depends on tire height, width, and also rim width.
From what I gather, this will change how the bike tips into corners, contact patch while leaned over, and stability.

 

[Cipher_R6]

Man I didn’t even put that together on Tacoma, what an idiot. Good call out.

I got the tire info from here…190/650-17 V01 | Stickboy Racing

From what I can tell, (Toyota) Tacoma World is referring to car (truck) tires on that site.
I don't think those measurements will translate directly to motorcycle tires.

Where did you find the measurements for the race-sized Bridgestones? I'd like to bookmark the reference.
-

Also, the other thing that I came across this morning while doing some research was tire profile.
How quickly the tire "slopes off" depends on tire height, width, and also rim width.
From what I gather, this will change how the bike tips into corners, contact patch while leaned over, and stability.

 

[Panici]

You've given me the key metrics of overall diameter and tread width anyways.

Since these vary between brand and models, I'll have to get the specifics of each tire I'm looking at into a spreadsheet.

Will work on it tomorrow and report back with what I find!

 

[Panici]

Okay here is what I've worked out.
In regards to those slicks vs street tires:

Front has about the same height as a 120/70ZR17, but runs narrower by 2-5mm depending on brand and model.
Rear has the same height as a 190/55ZR17, but overall width closer to a 180/55ZR17.


Think I will be going with a 120/70ZR17 and 190/55ZR17 to maximize contact patch when cranked over.
(And because I can't get an RS-11 in a 180 rear).

 

[SirBonus]

FYI - I had to change the front fender on my 03 in order to use a 120/70 with a tire warmer.

 

[Panici]

FYI - I had to change the front fender on my 03 in order to use a 120/70 with a tire warmer.

The 120/70 is just as tall as the 120/600-17 so I should be fine. Front fender is aftermarket carbon fiber anyways.