effect of tires on dyno numbers

hotsmoker350

hotsmoker350

New member
I recently put my truck on a dyno and relayed my numbers to the guy who did my headwork and mapped out my build. I ran cooper s/t maxx tires that only have one pulling season on them, which are aggressive mud tires and he said that they displayed somewhat false numbers. Below is the link to my thread that shows my mods and dyno numbers.
http://www.competitiondiesel.com/forums/showthread.php?t=168289

He said that if I ran say a harder road tire like a Michelin, my numbers would have been around 630 hp or so. Im just curious as to how much effect tire choice has on dyno output numbers. Any input as to whether tire choice matters on a dyno would be great. Thanks for reading or passing on your knowledge.
 
I think height and weight have most effect. Tread doesn't matter as long as you aren't spinning.

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yeah my M/T's weighed about 88 pounds each

the A/T's im running now .. weigh 67 pounds each .... massive rotational differences
 
I hear ya there ... I went from Hankook RT03's to Cooper AT3's ... picked up 1.8 average MPG as well ... not bad for an IDI international truck .. 87 F250
 
hotsmoker350 said:
I recently put my truck on a dyno and relayed my numbers to the guy who did my headwork and mapped out my build. I ran cooper s/t maxx tires that only have one pulling season on them, which are aggressive mud tires and he said that they displayed somewhat false numbers. Below is the link to my thread that shows my mods and dyno numbers.
http://www.competitiondiesel.com/forums/showthread.php?t=168289

He said that if I ran say a harder road tire like a Michelin, my numbers would have been around 630 hp or so. Im just curious as to how much effect tire choice has on dyno output numbers. Any input as to whether tire choice matters on a dyno would be great. Thanks for reading or passing on your knowledge.
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That was a fairly long loaded sweep, different tires would have made very little difference. Now on a inertia dyno it can be pretty significant.
 
DieselMonster said:
I hear ya there ... I went from Hankook RT03's to Cooper AT3's ... picked up 1.8 average MPG as well ... not bad for an IDI international truck .. 87 F250
Click to expand...

cant beat that tire for a DD. i love em so much i bought 2 sets. coming from yokahama anything is better tho!
 
Yeah , I do like the Irok's .. over all for a mud tire , they really do preform fairly good ... of course when your running 40+" tires , you need some real power to have any fun ..LOL
 
The dyno we use locally says he see's very little falloff from dot to dot tire no matter size etc. However he says there is alot of falloff from slicks to dot tire etc.
 
an inertia dyno measures how fast your tires spin up to max RPM, where as a load cell dyno actually measures the amount of torque it is taking to roll the rollers VIA torque and then if allows the opperator to smoothly roll the truck through the rpm's to gain a real world HP numbers while still measuring the Working torque ( which is noted by a load cell ) , Check out Mustang Dyno's web site ... that will give you some better info , or look up on google , might help a bit more .
 
So, would a Compound Turbo setup be better on a load cell to get the turbos spooled better? Also, would the numbers be higher or lower?
 
yeah, any lag at all will seriously affect numbers, compounds( twins) do and will lag, a load cell dyno like a Mustang unit, they can punish your truck all day, unlike an inertia dyno one run at a time..

the Mustang Dyno can do things like simulate load, grade, temps,ect .. and they will and can tune your truck to pull as hard as possible to find those weak links .

Sourceautomotive.biz these giys have one and its knowm as the punisher ..
 
I have always been told that slicks do calculate to lost hp on the dyno vs a street tire but I have never tested it back to verify. As for your scenario I would assume lighter and shorter tire would free up hp as well.
 
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