At this time, this email contains the most updated current technical information for North Americans about choosing larger tires and corresponding gears for the Syncro. If you have been waiting until somebody "figures it all out" before switching to larger tires and corresponding gears, things have advanced and there is enough information in this email for you to get going. It is written primarily for advanced syncroists and offroaders, and I have generally omitted some of the explanations about *why* some of the recommendations are made below as they are. For example, to go with bigger tires than discussed here, you are likely to be going to be using Seikel springs. I have not addressed below the reasons why those springs should be avoided. I hope in a subsequent email to address some of the larger and associated issues which will make it more friendly to approach for newcomers and more comprehensive as well. But if you want a quick study on "here is what to do" without 20 pages of detail, used this email until it is superceded. 

While this email was originally addressed to John Wessels in response to an email he sent to me, the email kind of took on a life of its own to the point that it included my final selection of gears and tire size, which is the first time I have published these specs to the list.

A note about the gears for the transmission: I am having special gears made up by Weddle for both 3rd and 4th gears in a ratio not yet used by other list members in the Vanagon, but in a ratio I judge to be more suited to the vehicle for the tire size I have chosen, which is rated 30.5" tall according to the manufacturer. These special ratios are deployed to keep the van driving pretty much with the same gearing characteristics of how the van comes stock with smaller tires. If you have been thinking of getting "ideal" big-tire gears yourself, now might be a good time to order while this production run is being made. That is because there is no stock of these gears, and they are being special ordered. These gears are only suited to tires that run approximately 680 revolutions per mile, however, and if you were going to choose a different tire size and/or use a different motor from the stock 2.1 litre motor, then you would want to choose yet different ratios from the ones I have given below. I address primarily only gears for tires that are rated by their manufacturers to be 30.5" tall, and tires that are rated by their manufacturers to be 29.5" tall. I have not addressed smaller tire sizes on the feeling that if you are going to go to all this trouble, you should mount the largest size tires that fit well and suitably in the vehicle, and for various reasons these two sizes are probably it.

I will gladly answer in subsequent or private emails any questions any of you may have about these and related issues.

The meat of the matter is basically that the tire I am selecting is 245/75/16 (rated 30.5" tall) plus 6.17 final drive ratio plus:

stock G     (for 9.49mph at 4,000rpm)   stock
stock 1st   (for 15.13mph at 4,000rpm)  stock
1.88 2nd    (for 30.43mph at 4,000 rpm)  an alternate non-North American factory stock gear
1.125 3rd     (for ~51.08mph at 4,000 rpm)  special gear ratio being made up
0.75 4th   (for ~76mph at 4,000 rpm)   special gear ratio being made up

(This is for use with a stock 2.1 litre motor with ratio rocker and computer chip upgrade).

These mph figures compare to a "stock range" as follows

      My Plan     vs.    Stock Range   Comment on My Plan
G      9.49mph        10.00 - 10.51   An improvement goes lower 
1st   15.13mph        15.95 - 16.76   Slightly lower   
2nd  30.43mph        29.28 - 30.76   Like our BFG 27x8.50/14 2nd  
3rd   51.08mph        49.23 - 51.73   Like our BFG 27x8.50/14 3rd 
4th  75.97mph         70.95 - 74.55   1.5mph faster than the BFG (better for 65mph speed limit)

"Stock range" is defined as the stock Michelin MXLs (819 revolutions per mile) that came on the vehicle new in the 80s up to the BF Goodrich 27x8.50/14 tires many of us run (782 revolutions per mile).

As you can see from looking at the above, this arrangement preserves the gearing in pretty much stock-like form, except that the G gear and 1st gear are a little lower, and the 4th gear is a little higher. So the effect is to "spread out" the gearing a little bit from its factory configuration.

I would have chosen a 4th gear that propels the vehicle even faster in 4th gear, but was swayed by list member comments about very sluggish acceleration results if I were to do so. Going much higher yielded very negative list member comments about having vans that would slow down if they were to "even see" hills, and other complaints about 4th gear acceleration. I was mindful that my Westfalia is often overloaded, so I erred on the side of caution.

The 2nd gear is a special gear Weddle has used that was a stock item in Germany for some of the Syncro transmission sold over there, and is still available new from the factory. Weddle has some high quality nice used ones for sale. The 3rd and 4th gears are installed on no vans I know of at present.

To recap, I believe this is the best plan to put into practice the largest size tire for syncro but it is the best plan only for those who are willing to change their rear trailing arms to 16" type, and is the best plan only for those who will run 2.1 litre motors. If you don't want to spring for 16" trailing arms or don't want to have the biggest tire you can fit well and elegantly in there, then I believe John Wessels size, which is 30x9.50/15 is the next best thing, and it is 1 inch shorter tire. People who are going to run 30x9.50/15 should probably change to 6.17 final drive gears and then have special ratios made up for gears 3rd, and 4th. I suggest the proper gears for that scenario below., which suggestion yields results similar to those that I have arrived at above for my chosen tire, which is 245/75/16.

When using Tim Smith's gearing calculator (in SIG below) always input tire size numbers which are imputed from manufacturers revolutions per mile data and do not use the tool that allows you to input tire sizes themselves, which tool will result in inaccurate calculations. Thus, it is useful for each tire to know its "effective" tire height, as calculated from revolutions per mile, rather than knowing that tire's "published" tire height. For example, the BFG 245/75/16 tire has a published height of 30.6", but going from its actual revolutions per mile of 680, the tire actually should be inputted into Tim Smith's gearing calculator as having a height of 29.66". Similarly, the tire Wessels/Euromog uses 30x9.50/15 runs at 705 revolutions per mile, which equates to 28.61" effective tire height for the purposes of using Tim Smith's calculator. The error you would have by now following this recommendation is fairly huge.

Note that the 16" tire size 225/75r16 produces effectively the same results for gearing purposes as Wessel's 30x9.50/15 tire and any gears chosen for one of those two tires may effectively be used with the other one. Similarly, the tire 215/85R16 gives effectively the same results as the tire 245/75/16, and any comments I make in this email about the latter tire apply equally well to the former, generally speaking.

That said, if I were to choose either 225/75/16 or 30x9.50/15 I would choose (instead of the gears I indicate above for 245/75/16) 6.17 final drive gear, plus the gears indicated immediately below:

stock G     (for 9.15mph at 4,000rpm) stock
stock 1st   (for 14.6mph at 4,000rpm) stock
1.88 2nd    (for 29.35mph at 4,000 rpm) an alternate non-North American stock gear
1.08 3rd     (for ~51.09mph at 4,000 rpm) special ratio to be ordered
0.726 4th   (for ~76mph at 4,000 rpm) special ratio to be ordered

(This is for use with a stock 2.1 litre motor with ratio rocker and computer chip upgrade).

These mph figures compare to a "stock range" as follows

      This Plan     vs.    Stock Range   Comment on This Plan
G      9.15mph        10.00 - 10.51   YUMMY...nice and lower 
1st   14.6mph        15.95 - 16.76   Lower   
2nd  29.35mph        29.28 - 30.76   Like the stock MXL 2nd
3rd   51.09mph        49.23 - 51.73   Like our BFG 27x8.50/14 3rd 
4th   76mph         70.95 - 74.55   1.5mph faster than the BFG (better for 65mph speed limit)

Asking Weddle to make up 1.08 3rd and 0.726 2nd gears would probably be a special order, but they can do it. Note that the actual ratio they make up will not be exactly 1.08 or 0.726 but something similar based on how the tooth counts fall. Chris will give you a choice of tooth counts and you can then make an election at that time and I can advise you on this decision as well.

Prices? Great news: Weddle has new reduced pricing for their 3rd and 4th gears. If I am reading this correctly, it is now only $195 for each set. The special 2nd gears are very pricey from the dealer, but Weddle has some used ones for sale for $175 for the mainshaft plus $55 for the mating gear. It is possible that if you want new gears, or that Weddle goes out of stock on its used 1.88 gears, that I will be your cheapest source of these special 2nd gears if you have to buy them new. You may email me about this if interested. Note that, if I am reading my emails correctly, there is NO extra charge from Weddle for making up custom gear ratios.

Accordingly, in the past many of us tried to fit our choices into sort of "traditional aftermarket" gear ratios that were going around, noteably 0.77 and 0.70 4th gears, and 1.17 3rd gears, which were alternate to the factory stock 0.85 4th gears and 1.225 3rd gears. But the simple fact is that the 0.77, 0.70, and 1.17 gears, easily available though they may be, simply do not provide ideal results for the syncro with the large tires discussed here, and so it is better to throw these numbers out the window and start fresh with whatever ratio that works best and then have those ratios made up by Weddle.

The paragraph you have just read represents an important evolution of thinking from the way we spoke about these matters only one year ago. My advice, and this is new: Don't use "on the shelf" aftermarket 3rd and 4th gears. Decide what ratio you want, then have it made up. This is one of the most important pieces of advice you will encounter in this document. Since there is no increased cost to doing this, one of the only downsides is time -- Weddle says it takes about 16 weeks to get the special order gears made and delivered whereas the off the shelf varieties are available immediately. The other downside I can think of is the issue of standardization, that basically it would be better if we would all be using the same gears and the same ratios so that we can sell transmissions among each other, interchange parts, etc. Accordingly, all else being equal, it would probably be better for someone new having gears made to stick with the gear ratios that others are using. One could refer to 1.125 3rd and 0.75 4th as "Derek gears", for example, and unless an additional objective or variable is being pursued, specify these ratios for use with 245/75/16 tires by default for the purpose of standardization.

For the record, as long as this email is getting out of hand (long), I will state that I am probably the lowest cost provider of brand new 6.17 final drive gears in North America, and 5.83s for that matter too but you can order these gears either through me or through Weddle. If you are having the work done by Weddle, you might as well order the gears through them. A change to 6.17 final drive gears is definitely part of the picture here and highly recommended for all syncros which may be driven off the road. Generally speaking, you will be able to order almost none of the gears discussed in this email through the VW dealer in North America. The Europeans sniff at the 6.17s and remove them from their vehicles at the first opportunity, but I think this is because they do not appreciate 1) how impossibly high the G gear is, and that it needs to be brought down as low as possible for real off-roading, which they do not do so much over there due to a lack of places to adventure, and 2) they have not yet appreciated how easy it is to simply change your 3rd and 4th gears to negate ill effects of the 6.17 has on gearing. Accordingly, I view their tendency to de-install the 6.17s as a mistake.

It will not come as a surprise that, as for where you should have the work done to install all these gears, I would strongly advise listers, particularly west coasters, to take the work to Weddle as a default. This company is our choice for this kind of work and has demonstrated a level of support to our community and willingness to acquire expertise related to syncro unmatched by any other transmission shop notwithstanding the small size of our market. Weddle willingly pioneers interesting ideas (in the American tradition) regularly, even those that subsequently didn't catch on, like the Loc-Rite system for adding the front differential lock to syncro. Weddle is also practiced at putting in your stock factory front differential lock, which is something you would want to do at the same time as changing the ring and pinions. The other choice for transmission work, this time on the other coast, would be Long Island's Dennis Haynes (Long Island, NY), who has rebuilt dozens of syncro transmissions that I know of and is a skilled mechanic and syncro owner and list member and you will see him listed as an officer of LIMBO (not that that really matters). 

Note that I think the selection of rpm vs mph at 4,000rpm for 4th gear is the most critical number to watch. Too high and the vehicle will be unable to climb hills well. Too low and the vehicle will be unable to drive acceptably fast on our 65mph highways. I judge 76mph as the best all around compromise figure for this setting. And even this figure probably means you want a ratio rocker and chip upgrade.

The G gear in none of these scenarios is acceptably low, but that cannot be helped. The point is to get it down as low as possible, which installing 6.17s accomplishes.

There is a mild degree of redundancy in the material toward the bottom of this email.

At 11:04 PM 7/31/01 -0400, you wrote:

Hello Derek,

A friend gave me a set of 5 265/80R 16's. They are Super Swamper radial
TSL's. They measure 31.5" tall. Now all I need is to find a set of rims. Also
need to get the rear trailing arms made but have been way too busy to do
anything.

Actually I need to know what the desire is to put such a tall tire on a
Syncro? Is it the ground clearance you are looking for? I have 16" under the
front diff with my 30" tall tires. Under extreme fender stuffing these tires
only rub slightly. Anything bigger would require stiffer springs to keep the
tires from moving up into the fender wells. The stiffer springs would cause
the Syncro to teeter toter on three wheels all the time causing a loss of
traction. The taller tires may give some bragging rights but for best
off-road capability I think that going any bigger than a 30 inch tire will be
going backwards. With the 6.17 R&P's the gearing seems good. I hope to get a
chance to do some more serious wheeling in the next month. I will get to see
how the G gear works out. So far it is only the rock crawling that seems to
need a lower gear.

I think that while the 6.17s help out the G gear the matter is hopeless and we should just forget about it. I will tell you what I do, and it is very expensive, is to slip the clutch when I am in bad situations where my G gear is too high. This wears out my clutches rather fast. But I can see no way out. Actually, I take that back, the way out is to use bash plates such as the wonderful one you designed for the front of your vehicle. With enough underside protection, one can not slip the clutch and just sort of bash your way along at high speed. :-)

It sounds like your are talking yourself out of your five 265/80R 16s. I think it is wise at this point to skip that big tire for the reasons you state since it would require you to make up special trailing arms, and as you say, it will have a detrimental effect on your G gear and you would then be advised to make up all new gears 2, 3, and 4 most likely.

My personal selection is to go with 6.17, of course, and then a tire that runs 680 revolutions per mile (BFG 245/75/16), probably the All Terrain Radial rather than the Mud Terrain,

and then these gears:
1st gear (stock)
1.88   2nd gear
1.125 3rd gear
0.75  4th gear (about 76 mph at 4000 rpm in 4th gear)

This will evenly spread out the gearing to a stock-like experience with those gears but with larger than normal spacings between the gears so the G gear is lower and the 4th gear is higher. 

While the tire I have selected is rated to measure 30.6" tall, I suspect it measures a little less in actuality going by other measurements I have taken with other tires.

This tire is only 1/2 inch further off the ground than your current tire, John, and I was influenced by your comments into settling on this particular tire. So the bottom line, I think your current setup is excellent and I would not change a thing except possibly some of your gears 2, 3, or 4. Possibly you have done that already. I think you really hit the nail on the head, John, and while my solution adds another 1/2 inch, I think yours may turn out to be have a cost benefit angle to it that makes it very appealing. Both solutions are good and valid and should be packaged better for other listers to understand and implement if they so choose. Some day I will do that but for now this email will have to substitute.  

The only reason I want you to mess around with your 5 265/80R 16 tires is to force you to help out looking for suitable 16" rims, a problem I have not solved yet, and, it would appear, is the last thing holding me back from putting my van back on the road in its new configuration. Based on careful re-reading of the tiretips article in my SIG, I now feel that ET28-ET34 is the proper ET for these 16" rims, but that they need to be wider than the stock 16" rim, which at 5.5" are simply too narrow for my chosen tire. The wheel should be 6.5" to 7" wide to use with size 245/75/16 tire, BF Goodrich says.

Too bad you couldn't fly out to see how the SyncroMog works. You need to
drive Coyote's Syncro too. I have taken mine out on the highway and it feels
stable even in a cross wind. I still need to do the wheel alignment though. I
have decided to leave the front sway bar off for now.

I actually tested my van without its rear sway bar on there and found that removing the sway bar brought no benefit in articulation. Accordingly, I bolted mine back on. I would like to know if you ever get test results from this metric.

By the way, anyone on the list who wants to replicate the gear selections I have made should email me or call me about this for supporting information about why. To sum everything up, I believe these gears plus the tire I chose is the best choice for the largest practical user-friendly syncro tire run within a 2.1 litre configuration (and possible ratio rocker and chip upgrade). Chris Weddle is going to put the order through to have those gears made up in a couple of days, and if you would like to pursue this direction you might want to get an order in at this time while a production run is being carried out. The gears are:

1.125 3rd gear
0.75  4th gear (about 76.2mph at 4000 rpm in 4th gear)

You can emailing either me or info@... or, in the event that yahoo blocks this email address from this email, by going to www.2weddle.com. In the event that neither of these works, or if you need some theoretical support, email me directly.

I think on the website Yahoo blocks the addresses so here it is cut up:

derekdrew
 @
 rcn.
 com