Just thought I'd post up some actual back to back data on running smooth dyno tires vs. the stock oem tires on a Raptor 700 build.

There has/had been some discussion on how much difference their is in peak hp #'s that can be obtained between the two types of tires.
Anyways, I just thought I'd show one example of the difference. These two runs were made back to back at the end of our dyno
session Saturday at Venom Performance. Remember that this difference might not be the same on all builds and power levels, but this is how
it shakes out on this 70 hp Raptor build.

Because of this difference, I still can't believe that some shops will invest 15-20k on a dyno, but won't spend $100 on a set a dedicated smooth
dyno tires!! Plus, for once I can't believe we remembered to try this experiment before pulling the quad off the rollers, lol.

** One thing to note on this dyno sheet **
The only relevant data of this sheet is the peak hp number, since the bottom scale is measured in speed (mph). The oem tires are larger
diameter than the dyno tires, so the red curve is shifted to the right in comparison. Hope that makes sense.

Blue: Dyno tires- 70.96hp peak

Red: OEM Raptor tires- 63.85hp peak

A full 7 hp difference... Same quad, same tune, same everything except the tire swap.





Later- Kris

thanks for sharing....

the more power to the wheels the larger the slip potential...

i complain when speed shops don't have dyno tires...or wideband A\FR sensors to track their jetting with the power curves..... but a "speed shop" that doesn't even own a dyno....that's something different alltogether....

every different brand of knobby tire has a different:

tread pattern + stiffness of rubber compound + weight......


so they all have varying degrees of less than perfect adhesion to the dyno rollers.... no 2 brands read the same.....


and...like i've said many times before..... you can't pin a number on it for every case.... more power will equal more slip.... a stock yfz with stock tires will be down 2.5~3HP over tires that stick to the rollers..... this modded raptor was down fully 7hp.....


the only thing for sure is you aren't getting real readings unless the tires are made to adhere to a dyno drum.... which knobbies most certainly are not......

Great info, thanks for posting it up!

For comparison, what are the dimensions of the stock tires vs. the dyno tires used? Were the stock tires on stock rims and the dyno tires on Douglas .125?

Another thing I did last week was test some other tires that a different shop was using for dyno work. They yeilded 5 more wheel hp on a 50 hp machine than my dyno tires.
So that was 10%.
Kris's situation showed almost 10% as well the other way.
We just illustrated that you can have as much as a 20% variance in hp readings based upon tires alone.
Please remember this when comparing dyno runs.

Wow, I do find that surprising! Wouldn't have thought you could see that much difference even between two different sets of smooth style "dyno" tires...

But yes, Kam is absolutely correct. It is virtually pointless to try and compare dyno numbers from different dynos. Just too many variables involved.

Later- Kris

Ghott-

As far as the tire dimensions, the stock tires were oem Yamaha Raptor 20" tall tires on oem rims.
The "dyno" tires are smooth "golf cart" style tires. I don't know for sure how tall, but I would guess
18" tall. They were mounted on douglas aluminum wheels, but I think they are sturdier than the .125's.
Maybe the .160's. Not positive on that though.

KBR????? which tires do u use? which ones did u test..... my dyno is a low reader which is ok,... im using 21 in tall DURO SCORCHER'S on a 10 in douglas RED

so knobby tires over dyno tires results in about a 10% loss in power