Help on Tires

KrazyMofo24

Jstas wrote: »

Junior, listen up. I'm not hell bent on proving you wrong. You ARE wrong. I know tires. I sold them for 6 years. I know ABS braking systems. I've been servicing cars for about a decade. I just recently gave up being an automotive technician. I have 10 years under my belt of professional experience. On top of that I have ooodles of actual racing experience with actual race cars. Not street cars with "legal racing" whatever that is. I know what wheel weight does to the unsprung weight, steering response and braking performance. I know what the difference between standard, non-ABS braking systems and ABS braking systems are. I've serviced brakes on more vehicles than I can remember. That's more than I can say for you judging by your responses.

I already gave reasons why you were wrong. We did not say the same things. But obviously, you are an "expert" so I'll let you go along believing you have some kind of knowledge that you didn't get from tirerack.com and keep **** up people's cars with bad advice.



KrazyMofo24, you want to put those tires on, go ahead. There have been multiple reasons in this thread stating why it's a bad idea. Some good, some very good and still some with real world experience (not just mine) and actual mathematics to back up why it's not the best idea. But it's your car, your money and your safety. Do with it as you wish. You obviously only want to hear what you want to hear, not what is true. Evidence by the fact that you believe a kid in Indiana cut and pasting from tirerack.com has "some knowledge of tires".

I'm done here. I thought there was enough evidence presented on why to not do it without having to chime in. But, guess not.

Look I appreciate your input, and it wasn't about only hearing what I wanted to hear. They were people on both sides of the argument, not just from this post like I stated earlier the mechanic at Firestone, dad, and girlfriend's dad. However I still wanted to be sure which is why I posted it here. You and Concealer both went into detail about it, and it wasn't until this post where you stated your prior experience on the subject, and with that it does help me decide. I mean I don't know about this stuff so when you say it can damage this, and someone else says its wrong, it makes it tough to say who's right.

Tirerack.com has some good prices, and definitely much cheaper than Firestone for 4 tires they quoted me $550 after the buy 3 get one one free deal. I found 4 tires for $200 less including shipping. So what I'm going to do is get the new tires from that local place for $160, and then I'll buy the other at Tirerack when I get some extra cash, and see if I can sell the P225's or give them back.

billbillw

concealer404 wrote: »

Y
Interesting bit of trivia: There was over a 2% variance in rolling diameter on the 99 Mustang GT from factory, depending on whether or not you got it with 16" wheels or 17" wheels. I'm pretty sure that they didn't design or calibrate the ABS system differently depending on what wheels it was going to have from factory.

It could be had with 245/45-17s or 225/55-16s.

Sorry bro, but you're wrong there. The difference in diameter between the two OEM sizes (225/55/16 vs 245/45/17) is typically less than 0.1" (<0.5%), which is no where near the .7" difference between a 225/45/17 and 245/45/17.

I do feel that mounting the smaller tire is a bad idea, but not because of the ABS, or it not fitting the rim properly. Why? The biggest reason is that you won't be able to properly rotate the tires to get safe wear out of them. You will also be giving up braking traction and steering grip. Bottom line, it will upset the balance of that car. As was said earlier, some cars come from the factory with differing sizes, but those cars are designed to be like that. The Mustang needs matching tires all the way around.

To the OP, do yourself a favor and get 4 new matching tires.
Price compare (incl shipping and possibly tax) from discounttiredirect.com, treadepot.com, Tirerack.com. See if your local stores will price match. Most of the time, I find it easier to just order the tires online, then take them to a trusted installer to mount/balance.

concealer404

Jstas wrote: »

Junior, listen up. I'm not hell bent on proving you wrong. You ARE wrong. I know tires. I sold them for 6 years. I know ABS braking systems. I've been servicing cars for about a decade. I just recently gave up being an automotive technician. I have 10 years under my belt of professional experience. On top of that I have ooodles of actual racing experience with actual race cars. Not street cars with "legal racing" whatever that is. I know what wheel weight does to the unsprung weight, steering response and braking performance. I know what the difference between standard, non-ABS braking systems and ABS braking systems are. I've serviced brakes on more vehicles than I can remember. That's more than I can say for you judging by your responses.

I already gave reasons why you were wrong. We did not say the same things. But obviously, you are an "expert" so I'll let you go along believing you have some kind of knowledge that you didn't get from tirerack.com and keep **** up people's cars with bad advice.



KrazyMofo24, you want to put those tires on, go ahead. There have been multiple reasons in this thread stating why it's a bad idea. Some good, some very good and still some with real world experience (not just mine) and actual mathematics to back up why it's not the best idea. But it's your car, your money and your safety. Do with it as you wish. You obviously only want to hear what you want to hear, not what is true. Evidence by the fact that you believe a kid in Indiana cut and pasting from tirerack.com has "some knowledge of tires".

I'm done here. I thought there was enough evidence presented on why to not do it without having to chime in. But, guess not.

None of what i said came from Tire Rack. You didn't say one thing that went against what i said other than that you feel like it's a horrible idea. The figures were all the same. The very next post you made after you condemned me for saying that it was ok to put a tire with a 2.8% rolling diameter decrease on that car, you then said that it was within factory tolerances and was ok. So which is it?

In terms of numbers, you did nothing but agree with what i said, but tried to turn it around like what i said was wrong, throwing in unwarranted personal attacks, which also happens to be something that you've mounted many tirades about even in recent history.

My location has nothing to do with my knowledge unless you want to make ridiculous immature generalizations about people's IQs in different areas of the US.

Considering that for the most part, we've made the same points, arrived at the same figures, how am i wrong, if you're coming up with the same information? Point out exactly what i said that was wrong, if you're going to lay a blanket statement that i'm wrong. Go ahead. Address it. I'm waiting. Be very SURE that you haven't said the same thing at some point. The only disagreements that we've had so far are 1) where you said that a smaller diameter package will trip ABS later, and 2) that i'm a punk kid with no experience and that i'm cutting and pasting Tire Rack. (Please provide proof.)

For the last damn time, i didn't say it was ideal. Ideal would be to have a 0% variance from stock. But the fact that it's a 2.8% variance, and that even you have said that it's not going to affect the main issue that you pointed out (ABS) in any meaningful way, should be enough for him to realize that it's not going to kill him, or be dangerous.

I didn't comment on your experience. I realize that you've had experience in the matter, i've seen your posts in the past. That doesn't give you the standpoint to sit there and tell me that i have no idea what i'm talking about because i wasn't a mechanic for 10 years. I do all the work on my cars, always have. I prep my cars for racing. And it doesn't really matter what you consider to be a "real" race car or not, the car that i was talking about where i took my own measurements is a race car. It gets raced in sanctioned events, bracket racing, SCCA autocross, NASA track days, HPDEs etc etc etc. Considering that it's an F-Prepared class car at this point, calling it a "street car" is justified really only in that it has a liscence plate and i can drive it to events if i please.

Nobody gave real evidence as to whether or not it should be done besides you and I. Ironically, you and i gave the same information.

concealer404

billbillw wrote: »

Sorry bro, but you're wrong there. The difference in diameter between the two OEM sizes (225/55/16 vs 245/45/17) is typically less than 0.1" (<0.5%), which is no where near the .7" difference between a 225/45/17 and 245/45/17.

I realize that. But contact patch and rolling diameter of the tire itself vs. contact patch and rolling diameter of a wheel AND tire package are two different things. It's <0.5% assuming that the 16" and the 17" tires have the same exact width, and they don't.

The 17s are 17x8.
The 16s are 16x7.

(EDIT)
Ah crap, i fat fingered the 16" calculations. You're right. My bad, thanks for catching. The point i just made still stands, though it is no longer relevant. Wheel width has an effect on rolling diameter, looking at just tire sizes will get you in the ballpark, but won't give you the exact numbers.

billbillw

concealer404 wrote: »

I realize that. But contact patch and rolling diameter of the tire itself vs. contact patch and rolling diameter of a wheel AND tire package are two different things. It's <0.5% assuming that the 16" and the 17" tires have the same exact width, and they don't.

The 17s are 17x8.
The 16s are 16x7.

Actual measured diameters ARE less than .1" difference according to various manufacturers specs. Which by the way, are typically based on using a 7" rim for the 225/16 and an 8" rim for the 245/17.


For example, measured specs of General Exclaim UHP (taken from Conti/General's website)
225/55R16 (on 7" rim) 25.7" diameter.
245/45/17 (on 8" rim) 25.7" diameter

concealer404

billbillw wrote: »

Actual measured diameters ARE less than .1" difference according to various manufacturers specs. Which by the way, are typically based on using a 7" rim for the 225/16 and an 8" rim for the 245/17.


For example, measured specs of General Exclaim UHP (taken from Conti/General's website)
225/55R16 (on 7" rim) 25.7" diameter.
245/45/17 (on 8" rim) 25.7" diameter

Yeah, i edited my post. I fat fingered the 16" measurement. Like i said, the point i was making, though it doesn't matter now, is that different wheel width will affect diameter versus if you just went by tire size not accounting for wheel. My apologies.

concealer404

Krazymofo, you have PM.