Will a new size wheel and tire mess with my speedo? - TCCoA Forums
 
LinkBack Thread Tools
post #1 of 11 (permalink) Old 01-30-2004, 02:57 PM Thread Starter
Seasoned PostWhore
 
lightevergreenfrost's Avatar
 
Join Date: May 2003
Location: Owensboro Ky.
Age: 35
Posts: 2,230
Send a message via AIM to lightevergreenfrost
Will a new size wheel and tire mess with my speedo?

I currently have 225/70/R15 and I am getting a set of 225/50/R16 for the Bird. Should I worry about the speedo being wrong after the change.

ps. I will eventually go with 235 (at least) for the car but the wheels are off a 93 and the tires a pretty much new so I will have to wait for the new tires.
lightevergreenfrost is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 01-30-2004, 05:44 PM
Seasoned Veteran Poster
 
mamberg's Avatar
 
Join Date: Aug 2002
Location: Philly
Age: 58
Posts: 890
try this:

tire size calculator

looks like your speedometer will read 9.3% too fast, or when your speedometer says 60 mph, your actual speed will be 54.4 mph.

At least you will be going slower than it says, not the other way around and risking a ticket.

One other thing to consider, if you still have a speed limiter (stock I think 106 mph), your new top speed will be only 96 mph, although your speedometer will still read 106 mph.

edit: isn't the stock size of tire either 205 or 215/70R15? the above numbers were assuming you speedo was right with the existing tires, compared to stock tires, the speedo would be a little more accurate.

Last edited by mamberg; 01-30-2004 at 05:59 PM.
mamberg is offline  
post #3 of 11 (permalink) Old 01-30-2004, 09:54 PM
Refrigerator Raider Hater
Moderator
 
GreenBird's Avatar
 
Join Date: Jul 2002
Location: Vermont
Age: 35
Posts: 11,719
WAY too short. Your going to have huge fenderwell gap, like 4". The tires will wear out fast due to being overloaded, and won't handle as well. IMHO, pull off the tires, sell them to an import buddy, and get some tires big enough for your car.




Matt "Looks Like Egon" Davis
96 Alpine Green V8
98 Audi A8 4.2Q in Racing Green Totalled
02 Audi A8L 4.2Q in Black

I buy my OEM Ford parts at 10% over dealer cost from Steve in White Bear Lake, MN.
You drive "like a man possessed"... by a woman!
GreenBird is offline  
Sponsored Links
Advertisement
 
post #4 of 11 (permalink) Old 01-30-2004, 10:06 PM
Seasoned PostWhore
 
Rich95XR7's Avatar
 
Join Date: Aug 2002
Location: Lawton, OK
Age: 45
Posts: 4,205
Send a message via Yahoo to Rich95XR7
I'm running 225/60/16's, and they are pretty close, about 3mph too fast on the speedo, but Ford's speedos aren't exactly known to be right on the money to begin with. Another choice, if you want something wider would be a 255/50/16.
Rich95XR7 is offline  
post #5 of 11 (permalink) Old 01-30-2004, 11:18 PM
Seasoned Veteran Poster
 
Join Date: Jul 2002
Location: Virginia
Posts: 965
Quote:
Originally posted by GreenBird
WAY too short. Your going to have huge fenderwell gap, like 4". The tires will wear out fast due to being overloaded, and won't handle as well. IMHO, pull off the tires, sell them to an import buddy, and get some tires big enough for your car.
I don't know if you saw my other request, but you didn't answer it. So I'll ask the question again;

How will running a SHORTER tire cause the tire to be over loaded and wear out quicker?
Eric Z. is offline  
post #6 of 11 (permalink) Old 01-31-2004, 11:32 AM
Refrigerator Raider Hater
Moderator
 
GreenBird's Avatar
 
Join Date: Jul 2002
Location: Vermont
Age: 35
Posts: 11,719
Quote:
Originally posted by Eric Z.
How will running a SHORTER tire cause the tire to be over loaded and wear out quicker?
The load rating of the tire is lower (generally), and while it's probably not unsafely overloaded, it is beyond optimum. Greater load on the tire means it has less abilty to corner. Think of it this way....could you run through an obstacle course faster with or without a 25lb weight on your back? Also, since the tire is shorter, it will rotate faster for the same vehicle speed. The faster the tire spins, the less grip it will have.

Not saying there will be a huge difference, but it would handle better with a properly sized tire of the same characteristics.




Matt "Looks Like Egon" Davis
96 Alpine Green V8
98 Audi A8 4.2Q in Racing Green Totalled
02 Audi A8L 4.2Q in Black

I buy my OEM Ford parts at 10% over dealer cost from Steve in White Bear Lake, MN.
You drive "like a man possessed"... by a woman!
GreenBird is offline  
post #7 of 11 (permalink) Old 01-31-2004, 01:23 PM
Veteran Poster
 
RAYBROADWAY's Avatar
 
Join Date: Aug 2003
Location: Havelock, NC
Age: 40
Posts: 811
If your set on the tires, you should plan on droping it a little. I tried them on before the drop and it looked like sh!t. That is the exact size I have on my SC's with Sprint Tech springs. I wish they were just a little bit taller, 60's would fill the wheel well perfict. You can see them click here for my cardomain

K&N FIPK73mm C&L MAF*22C plugs*FRPP 9mm wires*MARCH Performance Pullies*Sprint springs*Cat-back Flowmaster exhaust
95 Front end*SCP Cobra R Hood*93 SC rear bumper "smoothed out"*Ford Racing Cobra R's*OEM spoiler
Idaglo silver gauges w/ blue needles*All black interior with Mark VIII leather seats
RAYBROADWAY is offline  
post #8 of 11 (permalink) Old 01-31-2004, 11:12 PM
Seasoned Veteran Poster
 
Join Date: Jul 2002
Location: Virginia
Posts: 965
Quote:
Originally posted by GreenBird


The load rating of the tire is lower (generally), and while it's probably not unsafely overloaded, it is beyond optimum. Greater load on the tire means it has less abilty to corner. Think of it this way....could you run through an obstacle course faster with or without a 25lb weight on your back? Also, since the tire is shorter, it will rotate faster for the same vehicle speed. The faster the tire spins, the less grip it will have.

Not saying there will be a huge difference, but it would handle better with a properly sized tire of the same characteristics.
200 lbs difference in tire load rating is not going to effect tire wear when the lesser rated; smaller tire's load limits far surpass the requirements of the car.

Example:

Dunlop Qualifier GT's:
225/50TR15 1301lbs. x4 = a max vehicle weight of 5204lbs
225/70TR15 1753lbs. x4 = a max vehicle weight of 7012lbs

My bird with me in it, a half tank of gas and in full street trim only weighs 3960 lbs. No where near the weight limit of 225/50's. It's not going to be a factor.

I think you a couple things backwards. You have tried to draw a comparison of having a smaller tire to with running with more weight on your back. First off, a smaller tire is typically going to weigh less and we all know that less rotating weight = faster times. More rotating weight is going to decrease acceleration, braking and slalom times. Taller tires are also going give your car a higher gear ratio. Take my car for example, it has 3.73's. When I switch from the 27" street tires to 26" drag tires it makes my final drive equivalent to switching a 3.89 gear. The same theory should also apply to breaking.

In the turns the shorter tire will also perform better than and last longer because of the reduced amount of sidewall flex. While a shorter tire will rotate more times in a measured mile, I don't thing it will be so drastic that it should be any thing to prevent someone from buying the shorter version. The 2 tires I show above both have 440 tread wear ratings and 10/32's of tread so apparently the manufacturer doesn’t thing it will make much difference either.

As for this part of your post:
Quote:
The faster the tire spins, the less grip it will have.


I'm not sure what line of logic you’re using here so I will let you explain that to me a little more if you like. It just doesn’t make any sense at all.

I personally like to have my fender wells filled out. IMHO a 225/50/15 would look extra tiny and out of place on 'Bird that was not lowered 2+ inches. On a stock ride height 'Bird a 27" tire looks perfect. I'm running 235/60/16's right now myself. When/if the GP springs come in I'll switch to a 26" tire size. Probably a 255/45/17.

Eric
Eric Z. is offline  
post #9 of 11 (permalink) Old 02-01-2004, 12:08 AM
Refrigerator Raider Hater
Moderator
 
GreenBird's Avatar
 
Join Date: Jul 2002
Location: Vermont
Age: 35
Posts: 11,719
Well it seems we aren't in disagreement, you just think the effects would be less than I do...

I was only saying that a tire that can handle a greater load would perform better because less of it's stress will be from load, so there could more stress due to cornering.

As for the tire speed and grip...

ever driven on glare ice? if you go REALLY slow you can get across without a problem. however, if you go even 10mph, you will lose control and go sliding.

I will admit I didn't think about the mechanical advantage of a lighter tire. However I wasn't counting on a shorter sidewall, as I said "with the same characteristics".

Thing to do would be to compare to tires of the same design, one a 235/60-15 and one a 235/60-16 (as an example).




Matt "Looks Like Egon" Davis
96 Alpine Green V8
98 Audi A8 4.2Q in Racing Green Totalled
02 Audi A8L 4.2Q in Black

I buy my OEM Ford parts at 10% over dealer cost from Steve in White Bear Lake, MN.
You drive "like a man possessed"... by a woman!
GreenBird is offline  
post #10 of 11 (permalink) Old 02-01-2004, 09:54 PM Thread Starter
Seasoned PostWhore
 
lightevergreenfrost's Avatar
 
Join Date: May 2003
Location: Owensboro Ky.
Age: 35
Posts: 2,230
Send a message via AIM to lightevergreenfrost
Oh, I guess I forgot to note that the wheels and tires are already together on a 93 Bird. I am getting the whole car for $200 and selling the 5.0 thats in it for $100 if not more. The tires are brand new, they were put on the car just a few weeks before it was destroyed in an accedent.

ps. I did check, all the wheels and tires are fine, the accident did nothing to them.
lightevergreenfrost is offline  
post #11 of 11 (permalink) Old 02-02-2004, 10:25 PM
Seasoned Veteran Poster
 
Join Date: Jul 2002
Location: Virginia
Posts: 965
Quote:
Originally posted by GreenBird

As for the tire speed and grip...

ever driven on glare ice? if you go REALLY slow you can get across without a problem. however, if you go even 10mph, you will lose control and go sliding.

And WTF does that have to do with a shorter tire height causing you to lose traction on pavement? No matter the conditions, if you drive to fast for them, you’re going to lose control, regardless of the tire height. Sorry GB, that dog just isn’t going to hunt.
Eric Z. is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the TCCoA Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome