Loss of Power w/ Increase Tire Size

**COOKN** · 02-12-2008, 07:52 AM

I am curious as to the lost of power (acceleration) when you increase your tire size. I plan on going to MT Classic Lockers and Pro Comp All Terrain XT's with an increase in size to 305/65/17's. What are your thoughts on the lost of power? Will it be really noticable? Also---will the fuel milage reduce?

Thanks
TD

rutherk1 · 02-12-2008, 07:56 AM

In general yeah. You will lose power from both the added tire/wheel weight and the overall change in gearing. My old truck was a 2004 5.4 f150. I had 36 inch tires on it. It was a very noticable change. If you regear to something that will make the overall gearing steeper than what it was from the factory, it should make up for it.

**Mtbcoach** · 02-12-2008, 08:19 AM

Yes, it will impact MPG and power as rutherk1 said. With that size tire, you have probably added 50% more weight at each wheel and rotational weight is a power sucking demon. Then you have the difference in gearing, it will also increase the effective gearing.

If you have a MT, re-gearing is less expensive than in an AT but in either case, its an expensive fix to the issue. That is why it is best to keep the tire size under 33" and why added width is unnecessary, it adds substantial weight w/o substantial gains, IMHO. But, that viewpoint could open a whole other can of worms...

AZFJCRUZ'er · 02-12-2008, 08:25 AM

I noticed a difference just going slightly bigger and a little more agressive from stock. 3-5% on the odo and definately a power loss on the pedal. I would hate to see what a 305 mud tire would do.

**COOKN** · 02-12-2008, 09:12 AM

Quote:

AZFJCRUZ'er previously said:

I noticed a difference just going slightly bigger and a little more agressive from stock. 3-5% on the odo and definately a power loss on the pedal. I would hate to see what a 305 mud tire would do.

When you say slightly bigger---what size did you go to? And which wheels?

**COOKN** · 02-12-2008, 09:17 AM

Quote:

Mtbcoach previously said:

Yes, it will impact MPG and power as rutherk1 said. With that size tire, you have probably added 50% more weight at each wheel and rotational weight is a power sucking demon. Then you have the difference in gearing, it will also increase the effective gearing.

If you have a MT, re-gearing is less expensive than in an AT but in either case, its an expensive fix to the issue. That is why it is best to keep the tire size under 33" and why added width is unnecessary, it adds substantial weight w/o substantial gains, IMHO. But, that viewpoint could open a whole other can of worms...

I notice you have 16" wheels---the guys at 4Wheel Parts told me I had to stay with the 17's due to my rotors and calipers. I'm confused. Did you actually go down in tire size from the OEM's?

AZFJCRUZ'er · 02-12-2008, 09:22 AM

Quote:

COOKN previously said:

When you say slightly bigger---what size did you go to? And which wheels?

I figured you'd see the 275-70/17 in my signature with Helo Aluminum wheels (lighter than stock steelies).

**sand_man** · 02-12-2008, 10:21 AM

yeah, I would not go over 33" if it is your daily driver...

layonnn · 02-12-2008, 10:35 AM

4wheelparts is correct and wrong.
Some 16"wheels work and some don't because of the calipers. The TRD wheels are 16" so that proves they are wrong. As to which ones will work and which ones won't, WELCOME to the vast wealth of knowledge that is this forum. Someone will know.

**Mtbcoach** · 02-12-2008, 10:39 AM

Quote:

COOKN previously said:

I notice you have 16" wheels---the guys at 4Wheel Parts told me I had to stay with the 17's due to my rotors and calipers. I'm confused. Did you actually go down in tire size from the OEM's?

He gave you decent advise but there are a few 16" wheels that will fit. Like the TRD, my Enkei's and a couple steel wheels.

Mine came as part of a negotiation when I bought my in April right after the FJ Cruiser was introduced. The dealer put on a set of "bling" wheels that I didn't want and claimed he couldn't get the stock steelies. With a bit of work, we found these Enkei's that fit instead of the high priced, dealer add-ons they put on the FJ. It put the cost of the wheel add-on from $3k down to $1k which was more acceptable to me at the time...