WHAT SIZE LARGER TIRE WORKS BEST??

[Housewiz]

Finally brought that wagon home last weekend - found out it's an '87 - not an '86. Over 600 miles to VT and back in one day. 65 orig miles and totally solid/virgin sheet metal. No dents, bondo, nor rust.

With stock 13" tires, the tach is pegged at 3,000 RPM's. Way too high for decent mpg I think. I have plans to search for taller 13" tires to bring down the RPM's and then use 5th gear like an overdrive - just on flat and downhill roads. I'll be driving 95% highway miles (400/wk) so improving mpg is critical. Ideas???

[Housewiz]

Loops, that's 65K miles!!!

[Petros]

Congratulations on the buy, sounds like you got a good one (keep it that way!).

Changing tire size may not improve economy as much as you think. The factory designed the gearing to match the engine characteristics at part throttle cruise to get the best economy, usually. This engine is so under powered going to taller tires would make it even more of a pig.

What you want to do is see at what rpm does the max torque occur, and than choose a gearing (or tire size) that puts the rpm there at the speed you intend to drive it. The rpm where max torque occurs is where the max volumetric efficiency occurs, and should give you the beat economy. lowering the rpm to below this rpm will result in worse economy.

There was recently a thread on this topic of economy, you might go read it.

Rather than going to taller 13" tires, I highly recommend going to lower profile 14" tires and allow wheels. Taller 13" tires would make the handling really squishy and soft. The stiffer tires will improve handling, and the lighterweight wheels could improve economy slightly, espcially with some quality road tires (no aggressive tread snow tires, that will drop economy).

Post some pictures, the '87 has the brighter composite headlights, and a more modern looking grill.

[ARCHINSTL]

Ditto to Petros' comment about going to 14" wheels with lower profile tires helping handling (compared to taller 13" tires).
Having owned an '83 back in the day, I think Toy went to different gearing to improve acceleration - at the expense of highway revs and noise. Perhaps it figgered that most of these guys were being used in non-highway environments. Perhaps Subaru's comparable cars outdid the Tercs in acceleration?
When I went to the 14" Daisy wheels, I thought about a taller tire to bring revs back down to the '83-4 level, but went with 185/60R14 Kumho Solus KR21 (All Season type) to keep the speedo error negligible; now, if 99% of my driving were highway, I might have reconsidered...
As far as economy goes - there is just not that much difference between the '83-4 cars and the '85-88 gearing to make changing tires worthwhile.
Tom M.

[dlb]

i also support the 14" wheels w/ 185/60 tires. but, if you really want to try bigger tires to keep hwy RPMs down, i would try 15" wheels with lower profile tires. that way you don't sacrifice handling for hwy RPMs. i used to run 185/80R13 and just got a slight bit of rub on full steering lock so i just looked at a comparable 15" tire--looks like 195/60R15 would be pretty close.

the only other thing i would suggest is swapping the trans and diffs with the old 3.73 final gear ratio trans/diffs of the '83/'84s. i drove one for a day and the RPMs at hwy speeds were around 2500-2600. some folks find these old transmissions sluggish on acceleration but i honestly didn't even notice a difference. i rarely drive fast though. anyway, i don't think i would do it because what with your trans having such low miles on it, it seems like it would be a waste to swap it out. if you can do it relatively easily, it might be worth it as an experiment i suppose.

[4wdchico]

I'm running a set Michelin X Radial 185/65 x14 tires on a set of Mazda Miata Daisey wheels. They are 0.4" taller than stock and make the spedo more accurate.

Drives way better than the old 185/70x13 tires on stock rims.

[danzo]

I run 195/60-70 14's on my car (all bought used from my friendly neighborhood Mexiskins dealer) and am very happy with the resulting smooth ride. If you will be doing mostly highway driving you might consider ride quality above ultimate handling. Lower profile tires will allow you to turn quicker lap times on the Nurburgring, but they will also ride harsher, raise your engine speed and lower your ground clearance. Higher prfile tires will make your car slightly more sluggish, but if you are concerned about your car's acceleration I have some bad news for you. Don't worry about speedo accuracy; there are much more important thoughts to be had (healthy family/friends, world hunger, peace in the middle east, etc.).

Curious - how did a car from Vermont come to have no rust?

[Housewiz]

Excellent replies - thanks!!!

My wife drove the car back from VT. Don't think the wagon was totally legal (VT PLATES & registration) and felt she could wiggle out of a ticket easier than I. So long story short I haven't driven it yet and with an illegal scent, the cops around here would smell it a mile off.

It grew up in NM and retired to 2 month a year summer duty in VT. It's never seen winter salt - pretty cool.

We talked on cell phones on the way back here so that's how I know about the 3Krpm's @ 65 mph. Not sure how to post photos on this forum - I'm sure someone will chime in with a bit of show & tell.

It has the silver panels painted on the sides over a blue body. I'm leaning on a re-spray where those panels are to match the main body color.

[ARCHINSTL]

Steve -
That sounds like an unusual paint job - I don't think anyone else has mentioned this style.

As to posting photos - following is what I posted in another thread a while back:
"You can also post directly from your 'puter by going on down below the "Comments" box to "Upload attachment", then click "Browse," and then just look for the desired pix in your 'puter and hit "Open" in the window. It will then pop up in the "Filename" slot. Then just click on "Add the file." Click on "Preview" to make sure it is the photo you want to add.

A plus for this is that your pix can be left-clicked by a viewer and then it enlarges for finer detail.
I rarely use Photobucket any more (no probs with it - just like the "direct deposit" method)."
Tom M.

[North of 64]

Congratulations and please put up some photos

[tercel4wdrules]

the only other thing i would suggest is swapping the trans and diffs with the old 3.73 final gear ratio trans/diffs of the '83/'84s. i drove one for a day and the RPMs at hwy speeds were around 2500-2600. some folks find these old transmissions sluggish on acceleration but i honestly didn't even notice a difference. i rarely drive fast though. anyway, i don't think i would do it because what with your trans having such low miles on it, it seems like it would be a waste to swap it out. if you can do it relatively easily, it might be worth it as an experiment i suppose.

I did this experiment by going from a 4.10 to a 3.73 final drive and I feel as if it was a step in the wrong direction. I gained about 1-2 MPG depending on driving conditions (and probably because I was not driving as aggressively), but the penalty in responsiveness and acceleration in 5th gear in my opinion is not worth it. The trans turned out to have some issues, so I will be putting another 4.10 in there soon. I will definitely keep track and see if I notice any difference in fuel economy when I switch back. The best way is to maximize fuel economy is to follow those suggestions that have been mentioned previously.

[jp1985]

My neighbor was throwing away a brand new set of 13's in mud and snow tires she to0ok off her 80s corola will they work for a tercel wagon? i asked her for them and she gave them to me .

thanks

JP

[dlb]

most 13's should work on the stock wheels. i've never seen any that are too wide so i'm sure they're fine. good score!

[Petros]

wow, that is a good deal. they should fit just fine. BTW, do not drive on them unless you need to, my fuel economy drops from average 27-28 to about 20-22 with studded snow tires.

[jp1985]

I was thinking of taking them and having the studs taken off so i can use them year round. will that size tires still hurt my mpg that much when i get a tercel? if so i don't think i will use them.

JP