Any effects (speedo, etc) from switching from 17's to 20's on my 04 QC 4x4?

 

The size of your wheels will not effect anything. If you get larger tires then that's another story.

 

well if you go to 20s with lower profile tires in order to keep the same overall size then nothing but if yu get bigger tires with bigger wheels then your speedo will be off a lil bit depending on the tire size...if you just get a normal sized tire and not some big offroadin tires then it wont be off enough to really matter that much. one thing you might wanna take into consideration tho is this: my dad has 17s and i have 20s and we both have the 4.7 liter and when i stomp on the gas in his truck the tires will spin like crazy but when i do it in my truck i just take off faster. in some ways ive found that its good because you can stomp on it and go instead of losing traction and spinning the tires when you really need to get on it and go but on the other hand im a teenager and still like to have fun and show off and spin my tires sometimes and it will do it a lil bit but not like my dads. i can break em loose really good sometimes but other times its just barely squeals and takes off. not a really big deal but i still wish itd break em loose easier like my dads will. it might not matter to you but i was just giving you a heads up.

 

I have 2 sets of tire/wheel combinations--one for summer tires and the other for winter. For winter I use a set of Toyo Open Country AT LT285/70R17 on the 17 inch rims. For summer I use the Goodyear OE 275/60R20 tires. Both have 33" diameters and crank 632/636 revolutions per mile respectively. Thus, no need for any speedo recalibration. So, it depends on the size and profile of the tires you use.

Roger...

 

All I noticed was that it was a lot easier to squeal the 17's then the 20's. That is due to upgrading rubber quality.

 

2004 QC, what engine? 4.7/5.7? Rear wheel abs or 4 wheel abs? You will need to change your pinion factor in the abs controller, so milage and speed are properly calculated. rear wheel abs, you will need to change the pinion factor in the engine controller as well.

 

Not if the tires are the same diameter. 17" wheels with 32" tires will have the same pinion factor as 20" wheels with 32" tires. The only real advantage of larger wheels is stiffer ride, which gives better high speed handing and then of corse the "pimp look". If you are looking for better off road performance stick with the 17" wheels and get bigger tires (i.e. - 33",35",37"ect.).

 

Orrrr, it could be due to less rotational mass 20s are a lot heavier than 17s And it's worse if you don't keep the same diameter tires. [8D]

 

I'm curious about that last post...
17" Steel wheels with a butload of rubber must weigh as much, if not more, than aluminum rims with less rubber (for the same diameter.)
Which would have less rotational momentum???
Considering the weight of steel vs aluminum, I'd wager the 20" rims would have less mass, and therefore take less energy to spin up/down than steel with their associated excess rubber... Not to mention the additional sidewall flex in the high-wall 17"s.

Also, my brief, experience between the two leads me to believe the 20's do better on the HWY than the 17's.
I do admit, however, if I were spending more time off-road, I'd rather have high-wall 17's than road-efficient 20's any day.
For my needs, 4 times x year boat ramp and 3 x year deer camp duty, my AT tread 20's will do the trick.

 

Think about all that extra surface area on a 20" rim compared to a 17. I would bet the 20's are heavier.