terd ferguson

I did a search, no luck. I posted this on tire/wheel forum, no luck. Would running a smaller diameter but stock width tire on stock rims (i.e. 40 series instead of 50 series) have any negative effects? I know the speedo would be off a little (reading faster than you are going) and the odometer would be off a little too. Would there be any negative effects on the handling? Would those negative effects (if any) be outweighed by the benefit of faster acceleration? Please help and please be nice if you think this a stupid question. Thanks everybody!

Russ

Not a good idea at all for a myriad of reasons, the least being your new tires (rear)
would be nearly two inches smaller than stock. Wanna talk about a wheel well gap?

In order for smaller diameter tires to work and not look silly, you have to keep things
within an inch AND lower the car in the process. As for any negative effects being outweighed by increased acceleration I can think of one (using a 225/40/16). The quicker your car is due to running with 23-inch tires, the less time people would see how stupid it would look.

FWIW, I run on 205/45/17 and 225/40/17 with Tanabe NF lowering springs and my last combo was 205/50/16 and 225/45/16 so it's not like I'm alien to the concept but your "40-series on a 16" intent goes beyond practical application. Here's a few large pics showing my 24.1 and 24.3 inch tires. Lower than that? I wouldn't even consider it.

terd ferguson

I was just using 50 series versus 40 series as an example. A for instance if you will. I have rsr ti 2000 springs which would take care of the wheel gap. ON MY EP3, i WENT FROM 205/55/16 TO 205/50/16 from stock rims to spoon sports rims and it did'nt look stupid. It was lowered 1 3/4". but it had a much larger wheel gap stock than the S2000. Acceleration with the tire change felt like a huge improvement. I'm sure part of it was due to the considerably lighter rims, but not all. With a smaller diameter tire, you are effectively changing your gearing. I don't think that looks stupid. Also, with a smaller sidewall, it increases stiffness which is a benefit to handling. I don't see the problem. I just hear people go on and on about stick with stock widths which I can understand, but never diameter. I was just wondering. I think I might try it and post pics and then you can tell me if it looks stupid.


"Well son, you've tried and failed. The moral is...never try."-Homer J. Simpson

Russ

Terd, you seem to have completely ignored by response. I'm 42 years old and have
been doing tire/wheel modifications for years. The benefits of such I began to enjoy
nearly two decades ago. I'm not sure why you felt you needed to explain something
that I first discovered on a Triumph TR7 back in 1982 but let me try again.

You mentioned going to a 40-series tire and I told you that I went with a 50-series
in front and 45-series in back. I went from a stock tire diameter of 24.8 to 24.0 inches
and needed a 1.25-inch drop with my Tanabe lowering kit to close up the wheel gap
created by reducing the tire size nearly one inch. It still had considerable finger room
between the tire and wheel well but looked nice when I was in the car (6-4, 235-lbs)
which closed it up a bit more (another 1/2 inch if I can recall). If you're going to use a
50-series tire, then the combo I used would work.
205/50/16
225/45/16
Your gears should move to around 4.28-4.30 (I can't recall the exact #) and your
speedo error will be slight (3%) but it you use very light wheels as I did, it can
make a fairly dramatic difference in the car's off the line acceleration though top end
will be reduced.
When I said it would look stupid, I was referring to a 2-inch tire difference.
I'm not sure how low the RSR springs will go, but you will not be able to close
that kind of gap without the car looking like a low rider S2000 and for me, that WOULD
look stupid.
Always remember every yin has its yang. You seem quick to mention the
positives but there ARE negatives to such a setup. If you go to a 205/50/16,
in front, you're not removing a significant amount of sidewall to notice the difference
in handling however a 225/45/16 in the rear would be ok but bear in mind, it
will not handle as well as the stock set-up. You're not mentioning the wheels
you intend to use for such a set-up. No sense going low if you're using the
stock, heavy wheels. I used 13.8-lb Slipstreams.
The reason why people say stick with stock widths is because most people
don't have 23-years of rear wheel drive sportscar experience and need that stagger
to help them as much as possible when driving the car near its adhesion limits.
I like oversteer so a little tail waggin' makes me a happy camper. The
stock stagger is 1.6-inches which is fairly significant. It's even HIGHER with the '04
models. When you reduce the stagger to under 1-inch, you had better compensate
with some hardware underneath the car in front or at the very least, be aware
that at the limits, the car WILL behave differently than stock.

terd ferguson

You did not seem to read my post. 50 series to 40 series was just an example, not what I plan to run. It was just so even tards may understand what I am asking. I never claimed to want to reduce the width, just overall diameter. I did mention I may want to run a smaller diameter tire with the stock wheels. I challenge you or any one else to be able to tell the difference on a lowered car with one car having a one inch smaller diameter. That is unless you are close enough to read the tire size on the tire. I'm not going to get into a pissing contest with you Russ. I respect you opinion. I just disagree with the part about it looking stupid. I do not plan to run a 40 series stock width tire on stock rims. I do, however plan to minus size if you will one series smaller. When I do get new tires, I will send you a before and after and see if you can tell the difference. Fair enough?

Russ

Terd, do you not understand the relationship of aspect ratio to tire diameter?
You said in your first thread, "Would running a smaller diameter but stock width
tire on stock rims (i.e. 40 series instead of 50 series) have any negative effects?"
OK, let's examine this. If you want to run a 40 series 205, then it simply would
be a 205/40/16 would it not? That's a 22.4-inch tire which is a tire 2.4 inches
shorter than stock. Gonna drop your car 2.4-inches? No.
Now, a 225/40/16 rear tire would be 23.-inches, 1.8-inches shorter than stock.
What exactly do you plan to run? You asked a question and I answered it using
the parameters you provided. Give me the sizes you plan to run and I'll tell you
what I think.
205/50/16 (24.inches) I've done this already as mentioned above.
225/50/16 (stock size)
225/45/16 (23.9 inches) I've done this already as mentioned above.

You write "I challenge you or any one else to be able to tell the difference on a
lowered car with one car having a one inch smaller diameter" in the same thread
that I've clearly told you that's exactly what I've already done. Trust me, I would
know the difference and recognize it from 30-feet away. The sidewall alone would
give it away in addition to the height of the underbody from the road surface. I've
been doing "an inch lower" thing for more than year now.

terd ferguson

I don't plan on running a 40 series tire on stock rims. I plan on going down one size in the sidewall height in relation to stock. I plan on doing this for the added benefit of faster acceleration and a shorter sidewall height being stiffer to encourage better handling. I just wanted to know if there was anything devastating that might stop the rotation of the earth if I did this. The 40 series versus 50 series was just an example of a smaller aspect ratio. That's not what i plan to run. Do you understand now? How many times do I have to put that in my post? I'm finished with you.


"Trying is the first step towards failure."-Homer J. Simpson

Russ

Originally posted by terd ferguson:
I don't plan on running a 40 series tire on stock rims.

Then why on earth did you ask?

I plan on going down one size in the sidewall height in relation to stock.

Well, if the stock sidewall is 55, then one PLUS size down for the front would be 45
and that would be a 23.2-inch tire, not cool.
If you mean one size as simply 5mm, this means you plan on a 205/50/16 (4.01 sidewall, 24-inch diameter) for the front and a 225/45/16 for the rear (3.96-inch
diameter, 23.9-inch diameter). These are the identical sizes I ran for a year. You
keep avoiding my question. Are these the sizes you plan on running? It's a simple
question. Yes or no. If they are not, state your sizes. Good grief lad, this ain't
rocket science. You're only reducing the sidewall by .4 inches and what really
determines how a sidewall affects handling is it's construction. A Toyo T1-S has a very soft sidewall so if you went with that tire choice for this experiment, you will find, despite the .4 inch reduction in sidewall, that your handling will be worse than stock.

I am beginning to believe you have absolutely no idea what you're doing, otherwise,
you wouldn't have found the need to ask the question in the first place. You would
of simply done it. I'm done trying to teach you. Go create your Jeep.

f20cpwr

There are no intrinsic handling negatives with going with an overall smaller diameter wheel. I used to run 225/45/13, 21.0 in dia vs stock 22.7 in 185/60/14, when autoxing a Miata. Pretty much anyone wanting to be competitive in that class would run the same size because of the better gearing. That's the reason they were made in 13in vs 14in which would have been closer to stock diameter.

However this is a lot different than you want to do because it sounds like you want to keep the same size rim and tire width. Generally when going with a shorter sidewall you will lose a little tread width but that will also be greatly affected by which tires you would switch to. The new tires will have the most influence on how your handling will change.

terd ferguson

First of all, thanks F20 for a logical answer instead of "that will look stupid". Russ, obviously, you haven't read any of my posts. First I cited 40 series versus 50 series as an example of a smaller diameter tire. I keep saying I don't plan to run 40 series tires on stock rims. I plan to run 50 instead of 55 in the front and 45 instead of 50 in the rear. Yes, these are the same combos you ran for a year. I just wanted to know if the trees would stop growing and the earth would spin off it's axis if you ran a smaller diameter tire on an S 2000. I don't need a lecture about jeeps. Larger wheels create bigger gaps than smaller wheels. I told you I was finished with you. But no, you couldn't let sleeping dogs lie. I told you I respected your opinion, but now I don't even think you can read as I stated over and over again I didn't plan to run 40 series tires. So if you think my combo would look stupid, judging by your hunk of add-on junk you call an S200, I'd rather mine look stupid in your opinion. Your S 2000 is an abomination of all that is good and right with the world. I hate it had to come to this. I told you I was finished with you.


"You can't keep blaming yourself. Just blame yourself once and move on."-Homer J. Simpson