Tire size and speedometer calibration

[Mark-in-NH]

I have been wondering about this question for some time and I bet there are some guys here who know the answer.
My 2006 F-150 (purchased used) came with 20" (OEM) Roush chrome wheels. The wheels were already having minor chrome issues when I bought the truck and of course despite my best attempts at keeping them clean and polished, the New England winters are really taking it's toll on the chrome.
I brought this to Fords attention just after I bought the truck and while it was still under warranty and they flat out refused to warranty them. They Said take it up with Roush, they made them we didn't. Roush said, take it up with Ford, there the ones who put the wheels on the truck, not us.
So, I am thinking about replacing the wheels this year ( and they won't be chrome and they sure won't be anything made by roush)
My question is. Where as the trucks speedometer was originally calibrated for the 20" wheels, how much would I screw it up if I chose to drop back to a 17" wheel ?
I am contempalting just replacing the wheels with some Ford standard oem wheels.
Also, who has some suggestions for places to look for aftermarket wheels ?
I looked at alot on the internet but it is always nice to get reccomendations interlaced with personal experience.

 

[krusty the clown]

the wheel size is not as important as circumference of the tire. as long as it's fairly close the abs module can be programed for different tire size's.

 

[chadman]

Changing the diameter of the wheel itself will not affect the speedometer if you keep the overall diameter of the tire the same. Typically the factory keeps the same overall diameter regardless of wheel size. Post up what tire size you have now and I will calculate your tire size for the 17 inch wheels to keep the diameter the same.

 

[3798j]

Mark, Addressing that question of different size wheels and tires and what effect they'll have on your speedometer, check this out: http://www.mintylamb.co.uk/?page=tyre.htm
It allows two different tire/wheel sizes to be compared side by side. I think it might help.

 

[WNYflyer]

Here is another one. It even gives you the speedo error. I have used a similar one for changing out tires/wheels on a Corvette as well for downsizing for winter tires on my daily driver.

http://www.1010tires.com/TireSizeCalculator.asp

First place I always look for rims and tires is Tirerack.com and use this as a basis for my search for reasonable pricing. Been awhile since I got anything from them since I prefer to buy local but I know many people who deal with them a lot and been very happy.

If you are set on OEM rims I would hit the salvage/junkyards first to see what they have even though the truck is not that old.

 

[Stuart in MN]

Here's one more calculator that works pretty well for comparing tire sizes: http://www.miata.net/garage/tirecalc.html

 

[rburke65]

Google is your friend

 

[djd99]

I have been wondering about this question for some time and I bet there are some guys here who know the answer.
My 2006 F-150 (purchased used) came with 20" (OEM) Roush chrome wheels. The wheels were already having minor chrome issues when I bought the truck and of course despite my best attempts at keeping them clean and polished, the New England winters are really taking it's toll on the chrome.
I brought this to Fords attention just after I bought the truck and while it was still under warranty and they flat out refused to warranty them. They Said take it up with Roush, they made them we didn't. Roush said, take it up with Ford, there the ones who put the wheels on the truck, not us.
So, I am thinking about replacing the wheels this year ( and they won't be chrome and they sure won't be anything made by roush)
My question is. Where as the trucks speedometer was originally calibrated for the 20" wheels, how much would I screw it up if I chose to drop back to a 17" wheel ?
I am contempalting just replacing the wheels with some Ford standard oem wheels.
Also, who has some suggestions for places to look for aftermarket wheels ?
I looked at alot on the internet but it is always nice to get reccomendations interlaced with personal experience.

www.tirerack.com

 

[Mark-in-NH]

Ask and you shall receive. What a nice bunch of replies to come home to.
Thank you everybody.
The tire size on the truck is a 275/55/R20.
I am completely opened minded towards ford factory wheels or aftermarket. As long as their not chrome. I like the look of chrome, their just not suitable or practical for me and winter use.
I am also not all that concerned with keeping a wide rim. Those 55 series tires are nice to look at and are fine for the warm weather but again they are just not the most suitable for some of the conditions I have to drive in during the winter although I am amazed as to the places they have taken me with nothing more than an all season tread. I would probably be fine in staying with the wider wheel and just running a tire with a more aggresive winter tread.
I like the look of black wheels on a black truck so I am toying with that idea. I am concerned on how well a black finish would hold up. I see alot of black wheels that are advertised as painted. I like the idea of a machined or polished wheel and they seem to hold up the best to harsh environments.
I have found a bunch of places online for wheels and tires, Tirerack is one of them. These people also seem to have some decent pricing http://www.performanceplustire.com/.
I will also go to a couple of places locally (30 drive) and check with them. I to would be happier spending my money locally.
I will go do some reading at the sites mentioned but it doesn't sound like I will be adversly effecting the speedometer accuracy a whole lot as long as don't get to radical in tire / wheel size.

 

[chadman]

Mark, your tires (275/55-R20) are 31.9 inches tall. The two sizes I would recommend on a 17 inch rim are either a 265/70-R17 which is 31.6 inches tall or a 275/70-R17 which is 32.15 inches tall. Either one will work without any noticeable speedometer error.

 

[grcthird]

I have had good luck with TIRERACK. The shipping is what hurts you ordering from them. Keep an eye on the craigslist auto parts section for deals on stock wheels, you may even find someone to trade wheels with and save some $$.

 

[Striker]

I'd like to respond to your Ford warranty inquiry. I'm sure you had talked to the dealership as they were the ones that refused to warranty the wheels. Correct? If so Ford has a national toll-free number that you can call to escalate those types of issues. They should be able to help you when the dealer refuses to do so.

 

[Mark-in-NH]

I'd like to respond to your Ford warranty inquiry. I'm sure you had talked to the dealership as they were the ones that refused to warranty the wheels. Correct? If so Ford has a national toll-free number that you can call to escalate those types of issues. They should be able to help you when the dealer refuses to do so.

It was indeed my local dealer I spoke to initially. There response was that Ford motor Co. would not warranty the wheels because they were "Roush" wheels and not ford wheels. My arguement was that it was irrelevent WHO made the wheels, They came on the truck from the factory so that made them OEM and therefore should be covered under warranty. Needless to say my efforts were like trying to stay dry while ******* up wind.
I wonder if calling that phone number would have made a differance. Doesn't matter at this stage, the truck is well out of warranty.

 

[Torque1st]

Auto manufacturers pass the warranty thru on many items such as tires and wheels. Your recourse is through Roush. You will find that in the small print...

 

[JerseyJim]

275/65R18's used on 2009 Ford pickups are 31.9 inches in diameter. If you want to go with stock rims, look for TO's (take offs). Not unusual for folks who buy trucks to upgrade to different wheels and tires. You may be able to buy a complete set of tires and wheels at a really good deal. Just a matter of being patient and looking. Search Craigslist, Ebay.

 

[regguy1]

I have been wondering about this question for some time and I bet there are some guys here who know the answer.
My 2006 F-150 (purchased used) came with 20" (OEM) Roush chrome wheels. The wheels were already having minor chrome issues when I bought the truck and of course despite my best attempts at keeping them clean and polished, the New England winters are really taking it's toll on the chrome.
I brought this to Fords attention just after I bought the truck and while it was still under warranty and they flat out refused to warranty them. They Said take it up with Roush, they made them we didn't. Roush said, take it up with Ford, there the ones who put the wheels on the truck, not us.
So, I am thinking about replacing the wheels this year ( and they won't be chrome and they sure won't be anything made by roush)
My question is. Where as the trucks speedometer was originally calibrated for the 20" wheels, how much would I screw it up if I chose to drop back to a 17" wheel ?
I am contempalting just replacing the wheels with some Ford standard oem wheels.
Also, who has some suggestions for places to look for aftermarket wheels ?
I looked at alot on the internet but it is always nice to get reccomendations interlaced with personal experience.

The guy that mentioned this is correct
the wheel size is not as important as circumference of the tire
If I were making changes I would get a navi and check your speed now and note RPM / MPH relationships. Then when you make your tire change re check it to see if you're speedo is still accurate. Then you'll know for sure where you stand. ( clarification) Even if the tires make the speedo inaccurate the rpm / mph relationship won't change but you won't know your correct speed, so checking it now will provide you a good info base.

A GPS is an excellent way to verify speed and calibrate your speedo.
I have a good method for older cars with a cable driven speedo, might be of interest to restoration / hot rod guys. If anyone is interested let me know .

 

[richashley]

Check out newtakeoff.com for F150 wheels. It looks like they have some good deals. Chrome wheels and the extremely low profiles don't work very well here in NE Ohio either.

 

[chadman]

Check out newtakeoff.com for F150 wheels. It looks like they have some good deals. Chrome wheels and the extremely low profiles don't work very well here in NE Ohio either.[/QUOTE]

Very true!

 

[fordcragar]

I just bought new tires for my 05 Silverado, from TireRack.com. I'm lowering the truck, so I determined the diameter of the stock rear tires and bought new rear tires with the same diameter, as the old tires, so the speedo wouldn't be affected. Trying to stay with a similar look front and back, the fronts are a low profile 50's series and the rear a 60' series. The stock tires were a 245/70R15. The new fronts are a 225/50R17 and the rears are a 265/60R17.

 

[A29]

I took the easy way out. GPS is my friend.

 

[Mark-in-NH]

I am well familiar with "tirerack.com" I have been to their site many times before. Their prices certainly seem reasonable enough. Of course the S+H runs the total up pretty good.
I know I have been to the "1010tires.com" site before but after checking them out again I have concluded thet their sucking wind if they think I will ever pay their prices. I don't need tires and wheels that bad !
I checked the spare under the truck today and it is a 235/75/17 Hancock Dynapro.
I am going to do some pricing locally and keep my eyes open for some factory takeoffs. There is also a parts recycler near me and they may have something.
Out of curiosity I am going to take my GPS out of the car and put it in the truck to see how the speeds match up.

 

[Striker]

Auto manufacturers pass the warranty thru on many items such as tires and wheels. Your recourse is through Roush. You will find that in the small print...

That's correct, but sometimes there are exceptions. It all depends on the sales contract when the vehicle was bought.

I wonder if calling that phone number would have made a differance. Doesn't matter at this stage, the truck is well out of warranty.

If definitely wouldn't hurt if you called them. Explain everything to them thoroughly and be very polite and respectful.

The main issue here is when the wheels were installed. Were the wheels put on by the dealership at the request of the original owner or did they come installed from the factory as a factory installed option? As you stated it is a factory installed option you may have some recourse.

Either way a Ford representative from their toll-free number should be able to work with you to find a resolution. At the very least they should clear up who should be providing the warranty. If it is the wheel manufacturer the Ford representative should be able to reach out to the wheel company and straighten out everything.

 

[fordcragar]

I am well familiar with "tirerack.com" I have been to their site many times before. Their prices certainly seem reasonable enough. Of course the S+H runs the total up pretty good......................................................

I've found that the shipping and handling is almost the same as what I would pay in taxes, Washington State sales tax rate is 09.5%. Then I also have to add in all of the other charges that the state of Washington adds in for tire sales. They charge an environmental fee of $1.00 and a tire disposal fee of $2.50 these are for each tire.

I mount and balance my own tires, so when I buy them from The TireRack, they are shipped to my door. Then I don't have to waste my time going to different tire dealers looking for tires. I used to go to Costco and Discount Tire first, now I just order from TireRack, I don't waste all of that time and I'll save a few buck too.