The 24 Hours of Lemons Forums → Lemons Tech → Ride height question
I'm prepping a 94 Thunderbird. Apparently it originally came with 215 70 15's I'm considering putting a set of 225 50 15's on it which would reduce the ride height from stock by 3 full inches. This seems like a pretty big ride height reduction. I'm just wondering if this much of a ride height reduction might cause problems with axles or tire wear or maybe not permitting the suspension to move as it was intended? Anyone have any experience with this?
those tires alone won't lower the car 3", they aren't 6" shorter
They are 5" less in diameter.
Uh.. No Redo your math. They are 76mm shorter overall which will lower the car 1.5"
another person doomed by a combination of metric conversion and the sidewall height formula.
If you guys would just get it over with and go totally Metric we foreigners would save a lot in speeding tickets while on vacation.....12 inches in a foot? 5280 feet in a mile?Only the British could come up with this...
At least the British were smart enough to give it up once a better system was established 
Edward
76 millimeters = 2.99212598 inches but who's counting...
Dude, just go with the smaller rubber, cut the springs down, and we'll follow the sparks around the track.
Which engine does it run? The V8 or 6? Might even be good if you're on a tighter track. Also less to worry about if you're cutting springs. The writeup recently should let you take some of that guesswork out, if you're not so keen on surprises.
I don't bother doing the math. This is awfully handy.
http://www.miata.net/garage/tirecalc.html
Those spec Miata guys are good for something!
Doesn't help that I did the calculations with a change in rim size from 17 to 15 that I somehow read in there originally. 76mm it is indeed if you're not being lysdexic and subtracting 2 inches in rim diameter. Even less worry
To answer your question I doubt you'll have a problem with it on the track running shorter tires.
You won't have any problems with ride height.
Your tires will wear slightly faster(since they will rotate more per mile)
Your speedometer will be wrong(not that it really maters)
You will lose some top speed(theoretically not like you would get to the limiter anyaway)
You will get a little more pickup(theoretically. Change wheel size should act like changing the gears ratio)
I'd do it right away!
What tire brand?
KT
What tire are you going to get in a 225/50r15 anyway?
My car has less than 3.5" of ground clearance. It's a bit low. A 2x4 can not slide under the car on the 4" side.
We have had problems with the exhaust hitting the ground which doesn't make the exhaust guy real happy.
We are currently running 225/40r14s and once they're gone, I want to go to something like a 245/40r17. It will get the car up a bit and reduce tire RPM.
I think a low tire RPM will not only improve wear but keep the tires cooler.
Additionally, there are more tire options once you get into 17s.
First off allow me to reintroduce myself as Joseph Smith asshat extraordinar for starting a new thread on a false premise, as Jeff G said it would lower my ride height by 1.5 inches, and the overall diameter by 3 inches. Sorry about that fellas.
Hi Troy, the tires I was looking at were the Falken ZE 912's. in 225/50/15's although I'm sort of rethinking that now. My rims are only 6.5 inches wide so I'm thinking I'm not gaining much by stuffing at 225 tire onto a 6.5 inch rim. I might decide to go with a tire with a narrower tread and measuring rim (like a 205/50/15) and stretch those tires over my 6.5 inch rims and get a little more tread withdth that way, and get a cheaper tire with a stiffer sidewall, and a lower mass, in a wider variety of choices. On the other I'm thinking less rubber means more heat per tire, more wear, and lower overall gearing which I don't really need right now.
In terms of ride height I'm just guessing that anything that is within 2 inches of stock is probably ok. Anything lower than that and I begin to worry about whether or not the suspension arms and axles and other related components are operating too far outside their originally designed parameters and either not functioning correctly (maybe weird castor or camber angles) causing handling problems or causing excessive wear or stress on some component which might eventually fail (bigger problem).
Your car looked fast through the corners at Houston, I'm guessing that low ride height didn't hurt?
Ummm... changing tire size will change your ride height, but it won't change your suspension geometry.
Has nobody pointed this out yet?
In terms of ride height I'm just guessing that anything that is within 2 inches of stock is probably ok. Anything lower than that and I begin to worry about whether or not the suspension arms and axles and other related components are operating too far outside their originally designed parameters and either not functioning correctly (maybe weird castor or camber angles) causing handling problems or causing excessive wear or stress on some component which might eventually fail (bigger problem).
If the change in ride height is due to different wheel/tire diameter then you don't have to worry about the suspension because the positions of the linkage will be unaffected by the change. Now if you are adjusting ride height by changing the springs (length or rate) then you will need to pay attention to all the things you list above.
Your car looked fast through the corners at Houston, I'm guessing that low ride height didn't hurt?
A lower ride height will lower your CG which will help handling.
Edward
Ummm... changing tire size will change your ride height, but it won't change your suspension geometry.
Has nobody pointed this out yet?
That's not entirely true. While it won't change the physical linkages it DOES change the roll center as one component of the roll center calculation is the center of the tire contact patch.
That's not entirely true. While it won't change the physical linkages it DOES change the roll center as one component of the roll center calculation is the center of the tire contact patch.
If you want to play semantics about what I said, I only said changing tire size won't affect his suspension geometry (axles as well) since that's what he was worried about. I didn't say anything about the vehicle dynamics involved.
All in all, the answer to the OP's question is, "No, smaller diamter tire won't hurt your suspension or axles at all."
I love these threads! Everybody is an "expert" and its only Lemons! This whole Lemons thing is getting further away from the original intent every day. Next thing you know everybody will be giving "scientific theories" on global warming... Oh, wait... that's in another thread
Just do what you want, see how it works, and adjust from there - Its a great way to learn in a low cost risk environment
All you really have to worry about in this particular case is: do you have enough ground clearance? - who cares how much you lower it, what you care about is how much you have left? - SCCA IT requires 5" at the rocker pinch weld, but My STREET car has less than that. At full bump, its helpful to have a couple inches to spare, but YMMV.
The other factor is gearing - going with a lot smaller tires brings the revs up. In the case of my automatic Lexus, I did that on purpose to get more "squirt" out of the corners. Your car may or may not need that, but its doubtful its going to hurt anything.
As pointed out hundreds of times here, reliability, clean driving and good pitwork are what it takes to win. There have been plenty of winners that don't even put 100hp to the ground (we got as high as 2nd this way) Focus on this stuff and you'll spend less money and have more fun.
Just cut the front and rear wheel wells out and lower wayyyyy down, roll the
front wheel arches and send the exhaust up through the hood ala the Jag XJS.
No problem and it should only take an afternoon! Yuk Yuk!
At least the British were smart enough to give it up once a better system was established
You haven't worked on a mid-eighties Jag.
If you go smaller on the tire size, make sure and incorporate some brake cooling 'cause they're going to be working harder... or do I have that backwards?
If you go smaller on the tire size, make sure and incorporate some brake cooling 'cause they're going to be working harder... or do I have that backwards?
Backwards
INext thing you know everybody will be giving "scientific theories" on global warming... Oh, wait... that's in another thread
Using the Cow Fart Methane Emissions model we worked on the effects of the Lemons emissions at MSRH on the environment.
Our extensive analysis determined that, we needed more to drink.
Regarding tires, we run 225/40r14 on 14x7 inch wheels.
Shorter tires increase the brakes effectiveness. They do not change the suspension geometry.
Chopped springs will do that. Typically, lowering a car via the springs can also increase negative camber which is desirable.
Yes, my car is low and pretty flat in the turns. I got lucky and got some really cool suspension parts for not a lot of money. I figured out how to make some parts to adjust front camber too.
That, said my rear sway bar has no bushings, was still cut in half, sleeved and welded back together to get it in the car.
Lemons is about working with what you've got and being creative.
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