need crx tire advice

[larrybuck]

I have an '87 CRX. I have 175/70/13's now. I've read older post on here talking about Insight 15" wheels and taller tires.

I've owned my car 4/5 yrs., and have been quite frustrated that I'm turning 2,200-2,300 rpms at a mere 50mph. I heard the talk about taller tires changing that down to about 1,700 or so. I would love to see that.!! I don't have the scratch for high dollar LR tires, or buying even used 15 inch wheels right now. I wish I h

ad the diff. ratio of the original '84 1.3 !!!



Right now I need at least 2 better tires to even be safe. 2 are good.

My thought was to go to goodwill, buy a bathroom scale to buy light tires. Maybe I can trade off my 2 good 175/70's to help me get a better price on 4 used .. I want taller... so do I want 155/80's, 155/85's??? I'm willing to go skinny for a better CD, but what's the best height aspect for my stock rims??


If I'm staying w a 13inch every thing, is that difference going down to my dream 1,700 at mph. still possible, or is that rpm change only possible w like a 15 inch story?????


I can only go dirt cheap right now. HELP!!!!!!!!!!!!!!!!!!


I would like to pick a size common enough to be easily found used anywhere! Thanks!!!

[Ryland]

The Honda Insight has 14" rims and the stock insight tires will be about the right size for the CRX but they are an odd size that are hard to find, very few choices to choose from, stock insight tires of course will give you a boost in mileage by being low rolling resistance light weight tires.
155/80 R13 tires would be better, your crx is light enough that it can handle narrower tires, but for the gear ratio... I would say to do a transmission swap, $150 and a day of work and you will have a better gear ratio.
What trim level of CRX do you have?

[larrybuck]

I appreciate the help!

I hear other guys rattle off DX or HF etc... is there something on my vin# that would give me a clue as to how to answer you???

[Ryland]

Off the top of my head I don't know the vin number decoding, but an SI is going to be a 1.6L engine with fuel injection, the DX is going to be a 1.5L with a black steel air intake, the HF is going to have a silver aluminum air intake, DX does not have a tachometer but the SI and HF do.

[California98Civic]

The Civic Hybrid has 15" wheels I believe and a pretty good aero wheel surface. You need Low Rolling Resistance tires too. The size of the tire can make a difference in addition to the wheel. You might save the cash on the new wheels and look into larger tire sizes that fit your current wheels. Save $$$. Also, the overall diameter of the tire/wheel is inversely proportional to the RPMs rate. The power wheel/tire is basically a gear. You also want to take into account increased rotational mass from a heavier tire/wheel combo. See Sentra_SE's current discussion about switching to larger tires. He is having interesting results.

[some_other_dave]

The 87 CRX is the first-generation one. The Si will have a 1.5 liter engine with MPFI (Multi-Point Fuel Injection). It will also have a moonroof. The DX or Standard version (I do not believe there is a badge on it) will have a 1.5 liter engine with a carburetor on it. The HF version has an engine whose size I cannot seem to find out, and it also has a single carburetor on it.

Spinning at 2300 RPMs at 50 MPH tells me that this is most likely an Si, or at least has an Si transmission on it.

175/70-13 would have sidewalls of roughly 175mm * 0.70 / 25.4mm/inch; 4.8 inches tall. Two sidewalls contribute to the overall diameter, so that's 13 + 4.8 + 4.8 = 22.6" overall diameter.

A 155/80-13 would have sidewalls of 155 * 0.80 / 25.4; 4.9 inches tall. The overall diameter would be 13 + 4.9 + 4.9 = 22.8". That's a difference of about 1%. Not enough to justify the change IMO. (And I actually rounded the 4.8" down from 4.82...., and rounded the 4.9 up from 4.88... so the actual change would be even less.)

It's hard to find passenger car tires in any aspect over 80.

In order to bring your 2300 RPMs down to 2000 RPM, you will need to increase the overall diameter of your tires by 15% of your original 22.6", which is just about 4". So you need to get sidewalls that are almost half-again as tall as your current ones. Which IMHO is not going to happen.

Going up to 15s means you only need sidewalls that are 3" taller than your current ones. Still very unlikely. And going with bigger wheels than that will really hurt your in-town MPG, not to mention acceleration and braking distances...

And, of course, your speedometer will be reading a whole lot lower than you are actually driving, because it assumes the tires are the stock size!

The only real practical way to drop the cruising revs would be a transmission swap, or at least a gear swap. The speedometer would even read correctly (or as correctly as it does now anyway).

The folks on the Red Pepper Racing site know a whole lot about 1st-gen CRXes and the equivalent generation of Civic. You might look for more detailed info over there.

-soD

[Ryland]

Originally Posted by California98Civic

The Civic Hybrid has 15" wheels I believe and a pretty good aero wheel surface.

first generation of the civic hybrid had 14" wheels with the 4 bolt 100mm spacing, 2nd generation civic hybrids have 15" wheels but they use 5 bolts so they will not bolt on to older civics or CRX's.

[larrybuck]

I don't have an SI for sure!! Definitely have carb, my air cleaner cover is black, but I do have a fact tach, but no badging on the car.
I think they only badged w the 1.5 script the first couple of years.

The info that I've gotten so far is that the original early '84 1.3 CRX has a diff. ratio in the 'hood of 3.50-3.55 or so. The rest of the regular 1.5's I've heard were around 4.11 ???

I have some info that the 1.3 had a 4spd., not a 5; therefore I couldn't swap it in unless I only wanted a 4spd.

Then I wonder about garden variety Civic's all through the mid 80's that I think were 1.3's w 5 spds. That sounds perfect IF it had the mid-3's ratio.

I realize it was only that early 1.3 CRX that had the special alternator that was supposed to help achieve it's highway rating at about 67mpg.

I do have a sun/moon roof... can't tell if it's factory or not... in my climate I wish it wasn't there... it started leaking, and I sealed it shut ok, but it's still a slight CD blem even when closed!

I do have plastic front fenders instead of steel if that helps explain anything!!


It's like I have just enough knowledge about it to stay confused!!

I really appreciate the tire help. There's part of me that wants to go straight to a 155 for a better CD print, but a fraction of still wants the 70 aspect for looks, and my 1% of the time canyon racing by myself...which I would only PUSH a little in the dry only anyway!!! I'll have to sleep on this issue!!!!

Thank you everyone! Right now, I don't drive enough to justify a trans. swap!

[Ryland]

With the 1.3L engine from 1984-87 the civic hatch back came with a 4 speed while the 1984 CRX 1.3L (only year a CRX had a 1.3L) came with a 5 speed my understanding is that the gear ratio in top gear on both of the 4 and 5 speed transmission was about the same but that you ended up with greater spacing between them, however the CRX HF has a taller gear ratio giving you slower engine RPM at highway speeds.
All CRX's from 1984-87 had plastic front fenders and that bit in front of the hood is plastic too, CRX HF's didn't have a passenger side mirror, no rear wiper but they do have a little rear fin, no sway bars, most of the time they did not have a dash clock (altho it was a dealer option) and they did have an extra lower lip on the front bumper to bring it down lower and the radiator is tiny! 15" by 15"

The DX trim level has a hand full of options, like the dash clock, passenger side mirror, sway bars, maybe rear wiper... but I don't remember and a full size radiator.

The tachometer is a bit odd to find, but it's also not hard to swap out and apparently all the wiring is there for it already if someone did put it in from another car.
If it was an SI that someone swapped engines from, then it would have a factory sun roof as well.

[CapriRacer]

You might want to try 185/70R13's if you have enough room in your fender well.