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targabill
Samba Member
Joined: June 13, 2011
Posts: 22
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 Posted: Mon Dec 10, 2018 8:55 am Post subject: What is the largest tire size for an '81? |
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I've looked but this must of been talked about before..
I'm looking to drop my RPM's a lot..
What is the largest tire that will fit an '81 Westy.. I read 29" with lift spacer, will this work? I have a 175 hp Subi engine, with 174 ft lbs of torque which is plenty.
Also, does anybody know what wheel offset is used on the Vanagon? I was searching some wheels want to make sure they will fit.
thanks Much,
Bill |
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alaskadan
Samba Member
Joined: January 09, 2013
Posts: 1856
Location: anchor pt. alaska
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| Posted: Mon Dec 10, 2018 9:47 am Post subject: Re: What is the largest tire size. |
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| See if you can find someone with a set of rims with tires on them that you can try. Imo 28" is plenty tall with my taller 3rd and 4th. 4th is gutless at 50mph so you have to ride 3rd longer. I have the same engine as you. Surprised you haven't been snipped at yet by anyone, there's a boatload of tire threads on here. ET 30 to 35 is what you are looking for I'm pretty sure. I'm running some steel passat rims that are ET 45 without any mods other than opening up the center bore a little. |
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erste
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Joined: March 29, 2013
Posts: 1110
Location: San Francisco
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vanagonjr
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Joined: October 07, 2010
Posts: 3431
Location: Dartmouth, Mass.
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| Posted: Mon Dec 10, 2018 11:33 am Post subject: Re: What is the largest tire size. |
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| targabill wrote: |
What is the largest tire that will fit an 81' Westy.. I read 29" with lift spacer, will this work? I have a 175 hp Subi engine, with 174 ft lbs of torque which is plenty.
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Note, caution not to gear it so high, that you are too far out of the power band.
I'm not saying a 29" tire will do, that, but it might be wise to look at the rpm's an equivalent engine Subaru runs at and compare it to your set-up.
175 Hp is a lot compared to the original Type IV, but today it would not be considered much.
Look what I stumbled into when a quick search for a 175hp Subaru revealed a 2019 model.
"This wagon's base engine is decent when it comes to power and fuel economy, but don't expect to wow anyone with its acceleration" And that is a 3,622 lb car.
Of course, it only matters what you find sufficient, some find the original 67 hp in the 81 satisfactory.
_________________
John - 86 Wolfsburg Westfalia "Weekender"
Flint reversed 1.8T W/Passat 5-Speed
LiMBO (late model bus club) www.limbobus.org
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FAQ thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=525798 |
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Sodo
Samba Member
Joined: July 06, 2007
Posts: 9603
Location: Western WA
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| Posted: Mon Dec 10, 2018 7:25 pm Post subject: Re: What is the largest tire size. |
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I have the same Subaru engine, with 215/75R15 tires (27.7"). It runs about 3600 RPM on the highway, which you might (from the 3600 number) say "that's revving too HIGH!." And so did everyone else "back in the day" when they used to change to a lower ratio 4th gear (.78 or .70 4th). But its not pushing a slippery little car anymore, it's pushing a 4 - 5,000 lb brick. Now the general consensus is to use stock .85 4th gear with a Subaru EJ25 if you have 27.7" tires.
What's your transaxle maintenance plan with that big engine? Upping your maintenance game is best done __before__ you've ruined your valuable OEM VW transaxle. A rebuild and the lesser quality parts don't last 1/3 or half as long as an original VW trans (with 2 or 3x the HP). Best to preserve what you have with higher levels of maintenance AND go easy on the gas pedal. Resist the urge to romp on 2nd gear and don't drive 75mph sustained.
_________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50334
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| Posted: Mon Dec 10, 2018 8:45 pm Post subject: Re: What is the largest tire size. |
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I just have a 2.2 Subaru, but am very happy letting the engine spin using the stock gearing and tire size. Spunky off the line and seldom needs to down shift. I would be surprised if going 20% longer in gearing netted even a 2% increase in gas mileage, as there is nothing you can do to reduce the frontal area and few seem all that concerned about the amount of weight they carry.
Remember too that by increasing tire diameter to 29" you are increasing the torque on the CV's by about 20% over stock just from tire size alone which could lead to accelerated wear and bolt breakage. I for one wouldn't want to go there. |
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targabill
Samba Member
Joined: June 13, 2011
Posts: 22
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| Posted: Tue Dec 11, 2018 4:00 am Post subject: Re: What is the largest tire size for an '81? |
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My engine is out of a 2015 Subaru Forester.. It weighs 3615 ibs with 1500 tow capacity.. So I think the engine is fine for the 4200-4400 lbs Westy.
With the extra power, yes it is a very good idea to go very easy on the throttle.
But right now, when I let out the clutch in 1st I go about 10 feet and have to switch gears, could easily start in 2nd..
And my highway is 4500 rpms for 70 mph.. If I can get it down around 3300-3500 that would be good..
How often do you guys change you Transaxle gear oil.. Once a season??
More often is a good idea.
thanks much,
Bill |
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82westyrabbit
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Joined: March 02, 2015
Posts: 967
Location: Ma
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| Posted: Tue Dec 11, 2018 5:06 am Post subject: Re: What is the largest tire size for an '81? |
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| You have not said what transmission you have. Assuming you have the 1981 air cooled transmission. The transmission out of a air cooled van is higher geared than the transmission out of a water cooled vans that most of us are running already. My van has a air cooled transmission and 25.5 inch tires (215/65-R15). I would not want my tire any taller than that. I don’t remember what my rpm is at different speeds off the top of my head all though I have posted those numbers other places here but like 3200 rpm at 72 mph. The problem is as you gear the van up with bigger tires first gear get higher as well. Leaving me with poor performance for any off roading at all(like easy trails to get to camp sites). Good luck with your choice. John |
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Wildthings
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Joined: March 13, 2005
Posts: 50334
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| Posted: Tue Dec 11, 2018 5:32 am Post subject: Re: What is the largest tire size for an '81? |
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If you have the tranny with the NA Diesel gearing, you should have it regeared. IIRC the aircooled gearing would put you at about 3800 rpm at 70 mph with stock diameter tires.
With a stock engine you can change the oil every 100k miles and be fine, double the horsepower and much more frequent changes become critical. |
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vwhammer
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Joined: May 20, 2006
Posts: 998
Location: Boulder CO.
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| Posted: Tue Dec 11, 2018 8:03 am Post subject: Re: What is the largest tire size for an '81? |
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Don't know if I can really help out with your specific situation but I can toss out some more numbers from my set up for reference.
I am running a 2.0 ABA engine connected to the 1990 tin top Vanagon Auto.
Switching from the stock tire size, which is about 24 inches, to my new tire size 225/70R16 (28.4 inches) should drop the RPM from approximately 3500 RPM at 60mph to 3000rpm.
At 75mph we should go from about 4400 to 3700.
I had a Subaru with a 2.2 and if I recall the engine speed at 60 ish was about 2800rpm.
Not the same as the 2.5 but it might be a good starting point.
I do currently have a Jetta with a similar 2.0 engine as will be in my van and it currently runs at 2900 rpm at 60 ish with slightly larger tires than it had stock.
I do have a handful of performance mods in/on my engine so my gearing and tire size should be just about right with my torquey little 2 liter.
It will put the engine in about the same RPM range as it had while in the car I took it from and my power adders should help make up for the fact that my van weighs 1000 more pounds. |
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Sodo
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Joined: July 06, 2007
Posts: 9603
Location: Western WA
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| Posted: Tue Dec 11, 2018 12:17 pm Post subject: Re: What is the largest tire size for an '81? |
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| targabill wrote: |
| How often do you guys change you Transaxle gear oil.. Once a season?? |
OK I'll type another little book on over-engining a Vanagon transaxle. Not about the fun part of the big engine allowing you to keep up with traffic etc, no longer getting in people's way on the freeway (etc). The ugly part. I'm procrastinating again, so will offer some Tues AM Samba reading...
Here are three (or more) of the issues in over-engining.
1) More power is more steel in the transaxle oil. You have to get that metal out of your oil for even the SLIGHTEST hope of precision rolling elements like gears and bearings to last long. The metal comes quicker, so you have to drain it more often. In general, run it on the highway for an hour, tip the trans nose-up (front wheels high like 12") and dump out the oil and with it "dump out some of the metal". Think of how to get as much metal out as you can, every drain.
One misconception that I see often on TheSamba, is that the magnet has captured and is holding all of the metal that "was" in your oil. This is absolutely NOT true. The magnet holds "some", and the violent action off the R&P whizzing by at 700RPM washes much of it off every day. If your magnet has bare spots, that is a good sign. Once a magnet is completely covered, all bets are off.it's holding all it can, and the rest is dispersed around your trans. At that point it's just telling you that you reached steel pollution saturation "some time ago". If your magnet was covered, drain again after 500 miles, you still have a LOT of trash in there and need to get your transaxle to a "clean" baseline for it to last. You want to see the magnet showing "clean" at the next gear oil change.
A magnet that's pulled from a van that was parked will show more metal than a magnet pulled from a van that was run on the highway five minutes ago "to heat up the oil for best draining." When you run it on the hiway, the Ring gear whizzing right past the magnet at 700 RPM washes off a lot of the hairdo. But in turn, the mixing suspends a lot of metal in the oil that can then exit of the trans. It's FAR FAR better, to stir up your trans HOT and dump metal OUT, than to look at a nicely constructed xmas tree (from stationary oil) where SO MUCH MORE metal has simply dropped onto the trans floor away from the drain (thus won't drain out, thus pollutes your new oil).
You can get the metal out by various ways (not all of it), but you cannot restore burned oil.
2) More power is more heat. You have more than doubled the amount of power going thru that transaxle. Even 25% more power can seriously affect the expected lifetime and we're talkin' double HP!. Double the power is the same as reducing every gear size, every bearing size, to half size. If you drive fast, because now you CAN, 4th gear & your R&P will get hot cuz they're too small. This is related to usage. How fast do you drive with this big engine/small transaxle combo?
Make no mistake, double the HP means you have to up your transaxle maintenance BIGTIME. And driving FAST with that double HP (because you CAN) is what does it. Romping on 2nd gear is not a great habit to cultivate either.
Any component that transfers power from one to the other (such as gears), makes heat. Any bearing that supports that (excessive) transfer of energy makes heat. Anywhere there is movement and power transferring from one to another, with movement, there are losses and the losses are simply,,,,, HEAT. Gear teeth passing power will get hot whereas a spline connecting two concentric shafts will not get hot (not much). A ball bearing supporting a shaft that holds two gears from separating, will get hot as the balls mash into their races. OK got that? Now, add this. If the bearings and shafts flex 'apart' the gears' rolling contact becomes 'sliding contact', generating even MORE losses, = more heat. The oil at these locations will get way past it's max temperature tolerance, perhaps flashing into smoke, blackening your oil. You are damaging a tiny bit of your oil with every hot geartooth, by every hot ball on that hot bearing race. A fairly easy conclusion is that if you damage 1/10,000th of your oil 10,000 times, your oil is pretty far gone. This can happen quick with a half-sized transaxle. When your oil goes dark it's burned. But to know, you have to LOOK at the oil, not at the calendar or the odometer.
3) We know that with a stock engine (80-90hp), you can run the original oil 90,000 miles and the trans is still OK after 90,000 miles. The van is not dead, the quality-built trans likely has more than 60,000 miles left. Now in 2018, (for better or worse) that's already been done to pretty much every gear, shaft, R&P on every van, about 10 years ago, maybe 20 years ago. That horse has left the barn. Everyone has an old trans. Old transaxles are not as efficient as a new trans, they make the oill hotter, and generate more metal contamination too. And a "50% sized trans" (over-engined) is not as efficient as a "100% sized trans" (OEM engine). Just imagine if every owner changed the oil every 30k miles while the trans was pristine? And then every 15k miles after 90k? With only 90HP? There would be a lot of good tight transaxles out there. But the situation is the opposite. Now mix in some 130-175HP engine conversions with these old transaxles that shed more metal and that's where we're at in 2018.
And there are more issues. Including oil type, although I'd argue that oil type is WAY below issues 1,2,3 above. Racing oil can address item 2 above somewhat, but not after it's been contaminated by issue #1, and over time it succumbs to #2 as well and once burned, is less effective than the cheapest FLAPS oil you can get (if "fresh+clean" FLAPS oil of course). And we all know specialty oil does not rebuild a trans (#3). I don't know where oil is in this list if it's number 4,5,6 but it's not in the "top 3". Fresh oil addresses the "top 3 issues".
It all points towards a serious RE-LOOK at the maintenance regime applied to this essential and expensive, aging, van-stopping, and wallet-popping mechanical component.
So you ask, how often do I change my transaxle oil? The only answer I can really think of is "as soon as it loses it's translucence." How do you know if it's translucent? You can't tell by looking at a drip, you have to dump it out and LOOK. Maybe suck out a sample with a suction gun? I don't know, this is all kinda new cuz nobody really talks about developing the next transaxle maintenance regime for the "over-engined antique years". We're not experienced powertrain engineers we are enthusiasts. And even if you find a powertrain engineer, there is no field to draw from because powertrain engineers all work at the front end (new car, new market, new paying customer, engineered powertrain with engine-matched to transaxle, etc.).
But this:
| targabill wrote: |
| More often is a good idea. |
The realm is not "a good idea" it's the relationship between your maintenance effort, and the longevity that results. Less often is easier, but perhaps you enjoy your life more if the vans running. "More often" is you're under the van more often, but the transaxle lasts longer. That's fun for some. (like me). And maybe you can take longer trips where your passengers enjoy life as long except when the driver is ruining it by obsessing over the van.
It's a slippery slope. 
_________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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Jake de Villiers
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Joined: October 24, 2007
Posts: 5911
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danfromsyr
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Joined: March 01, 2004
Posts: 15143
Location: Syracuse, NY
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| Posted: Tue Dec 11, 2018 5:10 pm Post subject: Re: What is the largest tire size for an '81? |
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increased load (weight, and or larger tires)
Big Engine
stock transaxle
what's going to break 1st
opposite to layman thinking less rpm is not better..
it'won't save much mpg if any..
10% larger tires are like always going uphill
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| Abscate wrote: |
| These are the reasons we have words like “wanker” |
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E1
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Joined: January 21, 2013
Posts: 6528
Location: Westfalia, Earth
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| Posted: Tue Dec 11, 2018 6:20 pm Post subject: Re: What is the largest tire size for an '81? |
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There's more to consider here beyond tall tires changing your gearing...
... and that is space in the wheelwells vs. ride height, spring type, van weight, suspension travel, and intended use.
We've run 27s for a while now, and dragging around 29s sounds like a bad idea for a stock 2WD chassis for everything already written above.
Beyond, if there's a better way to trash these vans beyond going too fast and running driveline components too hard, I've yet to know what it is.
>>> Vote Sodo for President >>>
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman |
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Jake de Villiers
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Joined: October 24, 2007
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Sodo
Samba Member
Joined: July 06, 2007
Posts: 9603
Location: Western WA
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| Posted: Wed Dec 12, 2018 9:04 am Post subject: Re: What is the largest tire size for an '81? |
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Trying to reshape the transaxle maintenance dialogue amongst increasing contamination, specialty oil lobbyists and transaxle warming deniers....
There has been no collusion with Fuji Heavy Industries. I asked Fuji and he said they didn’t and I believe him.
_________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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danfromsyr
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Joined: March 01, 2004
Posts: 15143
Location: Syracuse, NY
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| Posted: Wed Dec 12, 2018 9:21 am Post subject: Re: What is the largest tire size for an '81? |
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and yet the official press secretary STILL hasn't ANSWERED the original poster's question
What is the largest tire diameter will fit a vanagon...
we'd need to know a few personal details before we can answer..
lifted, stock, lowered, what year(sure it's an 81?), what is the wheel well gap/height from the center of the spindle (cap) to the fender arch?
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| Abscate wrote: |
| These are the reasons we have words like “wanker” |
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?Waldo?
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Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Wed Dec 12, 2018 9:38 am Post subject: Re: What is the largest tire size for an '81? |
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| danfromsyr wrote: |
| 10% larger tires are like always going uphill |
Nope, that's a terrible analogy (I'm understating how bad that analogy is). It doesn't change the load, nor does it change the power required to meet that load. It just changes the RPM of the engine for any given speed and that change in engine RPM changes the amount of power the engine produces for any given speed.
As far as the OP's original question, unless noted otherwise, I'd have to assume all stock parts. I've fit 27" tires with a bit of room to spare. I have heard that 29" will fit with everything else stock. |
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Wildthings
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Joined: March 13, 2005
Posts: 50334
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| Posted: Wed Dec 12, 2018 9:45 am Post subject: Re: What is the largest tire size for an '81? |
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| On my '91 Multivan (Carat suspension) 27x8.5r14 tires rubbed badly going over uneven surfaces and when turning sharply like entering a parking space so they got removed. The same tires have worked fine on my stock 83 1/2. |
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E1
Samba Member
Joined: January 21, 2013
Posts: 6528
Location: Westfalia, Earth
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| Posted: Wed Dec 12, 2018 9:58 am Post subject: Re: What is the largest tire size for an '81? |
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Yep, exactly my point, WT.
There's way too many factors to just say "29s will fit." Our original front suspension bottomed out a new pair of 27s the first time I entered a parking ramp across the street from the tire shop!
Immediately traded them for 195/75s in knowing new suspension was a year or two away then...
So far as Dan's comment that larger tires are like "going uphill," that is dead right. So while I have no regrets going to 27", denying it takes more power to pull them is just inaccurate.
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman |
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