Too long i have suffered the jibes from fellow syncro owners about the teeny stock wheels and tires I use. Finally I found some wheels that might let me join the real mens club. They aren’t my first choice but the size, price, and offset were all right. They are 15×7 Mercedes 15 hole alloys from an early ’90’s 380SL. The offset is 25 which I kinda like, I wanted good clearance from tire to suspension components. Another good thing about these particular wheels is the thickness of the casting where the lug stud goes through. In this case it is only 11mm, some can be as thick as 44mm. I would have to install longer studs for any wheel thicker than 11mm and that was something i did not want to do (its a pain to do the front studs on a syncro). This wheel thickness will come up later.
Anyhoo, I’m not going to go into all the tire choices in this post. Im just going to show you what I did today to see if one particular tire would fit. The tire in question is a Yokohama Geolander GL AT-S 225/70 15. They have I think a load rating of 100, which is my, probably flexible, lower limit.
Here’s one bolted up. I sanded this one a bit (they all need painting) to try out a primer. The wheels have to have the stud holes drilled out to fit on the 14mm Vanagon studs. They were originally drilled to accept 12mm studs. You also have to get new lug nuts, the small seat ball type as opposed th the conical Vanagon variety. I got the hardware from T3 Techniques, and I also have received a lot of great advice from the owner Chris over the years.
Here is the small ball seat lug nut from T3 Techniques.
The trial fit was done on the rear wheel for a few reasons. First, the rears have the shortest stud projection, just flush with the stock steel wheels. With the alloys I got about 6.5 turns of the nut to hand tight. Now with the thread pitch being 14X1.5 mm that means the nut goes on 9.75mm. I would have liked more, 14mm would be the same as with the steel wheels. I don’t know if this amount of thread engagement is not sufficient, anyone have any thoughts?
edit: 9.3 turns would give me 14mm of thread engagement. That would be grand, but there is a German notice of requiring 6.4 turns minimum. So what to do? I am leaning towards longer studs for the rear. The front studs might be ok, there is a couple of threads exposed with the stock steel wheel, unlike the flush situation on the rears.
The second reason to check fitment on the rear wheels is to determine if rim and tire combo clears the trailing arm. I made a rough template of the tire profile from published data. What I am not 100% sure about is the sidewall height. I initially made the template so that the sidewall height was measured from the lip of the rim. When i held the template up to the wheel it interfered quite a bit with the trial arm. I thought this strange as I am sure I have heard of this size tire fitting the stock trailing arm, even on rims with higher offset. So i trimmed the template so that the sidewall height includes the tire bead section.
Not a great picture but you can see the notches I cut and you can see there is not only about 1/4″ of clearance between template and the pinch weld seam on the trailing arm. My template does not have radiuses corners so that might exaggerate things a bit.
I don’t know if this close up illustrates the clearance any better.
I’m reconsidering this tire size based on this quick and dirty measurement.
The other worry is that with a wide tire and a 25 mm offset rim there might be interference with the sliding door. Well no worries there, it clears with about 10mm to spare (close to my paper calculation).
I’m going to have to pour over the tire choices once more. Please, don’t mention Nokians, I know, I know.
During all this my friend was giving me skeptical looks.
#1 by famillysyncro on May 11, 2014 - 7:09 am
Nice rims Alistair.
Rear studs are easy too change and Chris got them in stock I am sure.
About your tire, I know 225 is wider than mine (and I had to “shave” the lip of the traling arm) but I am surprised as they are not as tall as mine (215/85-16, 3″ more in diameter….) but my offset is only 22 (30 for the rim and 8mm spacer) and it fit at the rear.
Did you consider your tire in 215/75-15?
Same rating but LT grade and only 0.3″ taller than your first choice and the sidewall height is only 6.35″
#2 by albell on May 12, 2014 - 7:00 am
I am reluctant to go to the 215/75 due to the gearing. I worry most about reduced G gear effectiveness. Apart from nokian and some hwy tread tires from other brands, it is tough to find an all terrain tire smaller than the 215 that has a load rating above 100.
I’m still searching…
#3 by famillysyncro on May 12, 2014 - 8:42 pm
This tire is about 1% bigger than the 225 you picked…. shouldn’t be too bad but I guess you were already at your limit with the 225/70-15
I understand what you mean, I would be really happy to find a 205 a little smaller than what I have now.
#4 by albell on May 12, 2014 - 9:38 pm
I think the 215/75 15 is close to 10% larger than 185/80 14 stock. The 225/70 15 is more like 6% larger. I may have t her numbers a bit of, going by faulty memory. I went to the local nokian dealer to see if I could get better price on hakkapelitta c in 205/70 15. I need to bring some evidence of low USA price to convince them.
#5 by famillysyncro on May 16, 2014 - 7:53 pm
I had some free time and thought about your tires.
Here is a link with your tire size comparison (hope it works):
So, the 225 is at 6.8% bigger, the 215 at 8% and the 205 at 2.5%bigger from factory.
Of course, you are better to do the math yourself with specs from the manufacturer to be sure.
Hope this help.
#6 by albell on May 17, 2014 - 8:13 am
yup, same results here.
I’m looking at Nokian Hakkapelitta C Van in 205/70 size. Expensive here in Canada but only about 100 bucks more for a set of 5 than the Yoko Geolanders 225/70. Ive come to the conclusion that you can’t find (easily) an all terrain type tire that is a close size fit AND has a load ration over 100. Except for the Nokians.