A tale of two tires (and wheels)

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zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

A tale of two tires (and wheels)

Postby zachmac » Fri Jan 26, 2018 5:54 pm

The were the best of tires they were the worst of tires.! :D

While I was rebuilding my engine and redoing lots of other stuff I decided to go to 15 inch wheels and aggressive tires. I'd had a set of Allison's 15 inch wheels on a previous 2000 FI car and was pretty happy with them. This time I choose some Team Dynamic 7" wide wheels with a 35 offset (I believe factory offset is 25). I put about 200 miles or so on those with a set of 205 / 50 Yokohama rubber. Aggressive to say the least.

More recently I decided to try a set of 13 inch original steel wheels with Kuhmo 185 / 70 13 rubber. I knew this would be very different and below are my findings / thoughts on the two setups.

First, here is what we are talking about, again VERY different choices.
Image
Image

So, here is what I knew, what I didn't know and what I learned.

Cosmetics:
No question the originals look just that, original. I personally also think they look pretty good and certainly make the whole car look "correct". The Team Dynamics wheels make the car look much more updated. Many people mistook it for a much newer car when it had them on. I know several posters here have said they are "too modern" but they definitely update the car's looks. Overall just comes down to personal preference.

BTW, I sourced a set of "plastic chrome" beauty rings from Amazon that are much deeper than the original metal ones but hey, they were $28 shipped for four, they'll never rust, and I like the way they sit all the way down into the wheel leaving only the "pretty part" of the steel wheel exposed.

Ride:
Night and day. The low profile Yokos on the 15 inch rims are borderline harsh. The transmit every bump and are generally very stiff. (BTW, the car is sitting on a set of Vicks progressive springs in both cases). The original 13 inchers with the much taller sidewall Kuhmos are very smooth. As you would expect the taller sidewall cushions the ride and absorbs a lot of the bumps. Overall a lot less noise, harshness and vibration.

Steering response:
Again, night and day but of course advantage to the Yokos on the 15s. The Team Dynamics with these tires provides almost instant change in direction with steering input. The car handles very neutral with little over or under steer. (All the steering and suspension components are new in both cases as well). The first time I drove it with the stock 13s and the taller sidewalls I expected slower response but I was surprised by the magnitude of the difference. It takes considerably more steering input before anything happens and there is definite understeer. This is all of course expected with the narrower tread and higher more flexible sidewall but I was again surprised how much different. Not dangerous or anything, even fun, but VERY different.

Grip:
Again, obviously the 15s and Yokos provide more grip. I have done some fairly high speed cornering with that setup and never felt like I came anywhere near the limits of the grip. I haven't pushed the new setup much yet but clearly I'll find where they start to lose grip much sooner. On the other hand they would probably "let go" much more gradually and give some warning whereas I think the wider Yokos might be a rude awakening if they got there?

Low speed steering:
Advantage stock setup. One of the main reasons I explored this option was because the steering effort parking and turning at slow speed was SOOOO high with the wide tires. They stock ones one the other hand are very light to steer at slow speeds, like I remember these cars being when I drove roommate's cars new in the 70s.

High speed steering response:
As I mentioned above, the narrower taller sidewall tires respond much slower to steering input but not in an unpleasant way. Again, just like they drove in the day (although 185s are quite a bit wider than original 165s or 155s). The wide setup provided very quick steering response at any speed but not so much as to be twitchy. It did tend to tramp in ruts and uneven roads more however.

Alignment:
could never achieve factory specs with the wide setup (nor did I expect to) but I was able to dial in good enough number for straight tracking and good return to center and even wear. Not really an issue provided you have a good shop that will work with you. I am able to get to factory specs of course with the stock wheels.

Fitment:
On a related note, I ran the wider wheel with two stock spacers both front and back. Back was fine but with the wider rims and tires and 35 mm offset the fronts did rub the upper control arms slightly if at FULL lock. Never and issue otherwise but it made really tight turns when turning around or parking a challenge. The obvious answer is of course some wider spacers, probably 15mm. I see AR is selling sets reasonably now. That would also actually allow that setup to dial in closer to factory alignment specs.

So, where am I headed?

First, I need to spend a lot more miles driving the stock setup. I like it a lot so far. They car doesn't handle nearly as well and that is FUN! It is also much more pleasant to drive slowly (steering effort) and rides a lot smoother. I have a very different daily driver if I want to do fast and corner hard (2010 E63) so I think I prefer this car old school. Plus, I was very pleased with the stock steel wheel look once I painted them and added the hubcaps and beauty rings. Meanwhile the other setup is all cleaned up and properly stored in the garage while I decide. :D

If you want a Spider that handles like it is on rails and has great neutral steering response, AND can live with a somewhat hard ride and LOTS of low speed steering effort, go with the wide setup. Maybe with a 195 instead of 205? For now I am thinking less handling might just be the way to enjoy these cars more. Thoughts?
Last edited by zachmac on Sun Apr 15, 2018 9:28 am, edited 1 time in total.
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

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phaetn
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Your car is a: 1974 Fiat Spider 1800
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Re: A tale of two tire (and wheels)

Postby phaetn » Fri Jan 26, 2018 8:46 pm

Not to hijack your thread, but I have gone through a similar experience.

I went from 185/70-13 Toyos on original steel rims to Dunlop Direzza 205/50-15s on Cromadora-esque alloys (i.e. replicas). I have Koni shocks and A/R lowering springs, too. I think the new wheels are in keeping with the original style, but the stance and larger wheel size make the car seem much more planted (especially the fronts with so little clearance).

Image

Personally I love the bigger wheels. Handles like on rails. Get better foot-down traction, too, as with the open diff I used to spin the inside rear wheel a lot more.

One of the reasons I finally switched was that I trashed an original rim understeering into a curb after a particularly spirited half a roundabout in cold weather. I don't want that feeling again. :)
https://www.flickr.com/photos/1974_fiat ... 764319972/

The wider tires definitely pull and hunt on grooves, but I got the alignment right by a good old-school guy and I'm happy with it. I'll trade the extra steering effort and full lock-rubbing for the handling any day. I'd never go back! :mrgreen:

Cheers,
phaetn
1974 CS1
32/36 DFEV; CompuTronix ign.
9.8:1 c/r; 40/80 intake cam w/ Isky springs
Vicks' SS header & adj. cam pulleys
A/R's progressive coils, Koni Yellow dampers
205/50-15s on CD-66 style rims
Momo wheel, Corbeau seats w/ 5 pt belt
pics and HD vids

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nelsonj
Posts: 394
Joined: Thu Oct 14, 2010 5:37 pm
Your car is a: 1972 Spider 124

Re: A tale of two tire (and wheels)

Postby nelsonj » Fri Jan 26, 2018 10:45 pm

Great write-up and thanks for posting.
BTW - do you have a link to the source for the beauty rings? I was thinking about swapping out my originals, but wanted to make sure the new ones fit. I think they look really good.

Peace.
Out.
Image
Simi Valley, California
Spider 1800
Romans 10:9

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azruss
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Your car is a: 80 Fiat 2000 FI

Re: A tale of two tire (and wheels)

Postby azruss » Sat Jan 27, 2018 12:47 am

I made a similar upgrade. I went with Rota 15" rims with 195/55. I purposely didn't go to 205s because I didn't want to create any more heaviness than necessary. The ride is harsher as expected. Mainly on residential streets. Runs smooth as silk at highway speeds. I am running lower tire pressure than I did with 185/70/13s. My biggest objections with the high profile tires was you had to wait for the sidewall to load in a corner before you got stability. This makes it trickier to corner hard. I also didn't want to be surprised with tires that would under perform what I drive with every day. I've known guys that have put very valuable cars in the ditch just for this reason. Lastly, I went with the change for the greater selection of 15" tires.. not just for today, but when I have to replace the tires 10 years from now.

zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

Re: A tale of two tire (and wheels)

Postby zachmac » Sat Jan 27, 2018 7:47 am

nelsonj wrote:Great write-up and thanks for posting.
BTW - do you have a link to the source for the beauty rings? I was thinking about swapping out my originals, but wanted to make sure the new ones fit. I think they look really good.

Peace.
Out.


eBay here: https://www.ebay.com/itm/13-NEW-Plastic ... 2749.l2649

They delivered quickly and fit perfectly.
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

Re: A tale of two tire (and wheels)

Postby zachmac » Sat Jan 27, 2018 7:54 am

Phaeton,

Ouch on the original rim!

I agree with everything you said. Not a high jack at all as I was meaning to encourage discussion and other's experience.

Like I stated, I haven't had enough time on the 13s to make the final call yet. I was able to buy those rims, bead blast and paint myself, and add the tires, beauty rings and hubcaps for about $400 all in so I can probably easily re-coup my investment if I change my mind but for now I still need more run time. Even in the couple of short drives I totally experienced the under steer and the "loading time" for the high sidewall in a corner. Like I said, for now the 15s are carefully stored while I sort it out.
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

Re: A tale of two tire (and wheels)

Postby zachmac » Sat Jan 27, 2018 7:55 am

azruss wrote: Lastly, I went with the change for the greater selection of 15" tires.. not just for today, but when I have to replace the tires 10 years from now.


That seems to be the driving (no pun intended) reason for a lot of folks but I think with Fiat and others bringing smaller cars into the US again it is actually getting to be less of an issue to find 13s. I had at least a dozen choices.
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

Re: A tale of two tire (and wheels)

Postby zachmac » Sat Jan 27, 2018 10:04 am

phaetn wrote:I'll trade the extra steering effort and full lock-rubbing for the handling any day. I'd never go back! :mrgreen:

Cheers,
phaetn


So you do also experience some full lock rubbing? I don't remember that when I was running Rotas on the 2000 FI car. Are you running any spacers? What are the offset of your wheels.

BTW, I think those Cromodora replicas are very nice!
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

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phaetn
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Your car is a: 1974 Fiat Spider 1800
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Re: A tale of two tire (and wheels)

Postby phaetn » Sat Jan 27, 2018 12:04 pm

Thanks, Jeff.

The wheels are 15"x7" with a 20mm offset.

I haven't used any spacers as A/R said they would fit. Happily, they did. :lol:

While it's a very, very close squeeze, I don't think the wheels actually rub much against the sway bar. They certainly do when the car is lifted off the ground at full lock, but I haven't really detected it when planted and the geometry changes with the weight of the car. That said, I do tend to avoid a full lock. How often is it needed anyway? Or maybe my full lock is just a new, lesser full lock. :P

What IS a very close fit is to the back of the wheel well:

Image

To be fair, this pic was from before the new alignment and the right front caster was way off. I could tell not only because of the slow return to center of the steering wheel, but also the sway bar didn't seem to fit evenly in the outboard mounting bushings. It was perhaps due to the earlier curb climbing incident on the other side that knocked everything askew and may even have bent the unibody (front door gap definitely changed). I kept fiddling with toe and could never get it right but the alignment after the new wheels finally sorted it out. There may be more space now but it hasn't proven a problem and I still like the beefier look fore and aft.

Image
(still a pre-alignment pic)

I grin every time I see the car from behind and see the wider 205 rubber...

I think the new wheels transform my car from an elegant yet perhaps somehow under-performing classic, seemingly out-dated or even quaint to a modern eye, to classic Italian engineering with beautifully sculpted lines that now hints at surprise performance with a slightly aggressive but not domineering posture. I'm not sure how else to express it. I know it's not for everyone, and I'm certainly not a purist as you can tell by my more modern seats. I guess I like to mix a bit of a performance boost with still classic looks... :mrgreen: I'm not naive and I know it's nothing close to a race car and that any modern econo-box likely out-performs it in every category but handling and sound. :twisted:

Here's a direct side-by-side comparison as I was switching wheels over:
Image

I can honestly say that the wheels and tires are singularly the best money I've spent on the car in terms of both looks AND performance.

Sorry to go on and on and wax lyrical about the car and toss in so many pics. Can you tell I'm missing it?!? I haven't driven it in probably twelve weeks as I had to store it early because of a head gasket failure. Hopefully only about eleven more weeks to go before it's on the road. :) Engine is hopefully sorted and I'll have a test start later today. It's been a weird year with a lot of snow and a lot of melts and I hope rain washes away the salt by very early April...

I'm conflicted: I downhill ski with my girls so I want a lot of snow in the winter, but then when spring skiing is over I want it all gone right away and the roads immediately clean so I can get the Spider out. :mrgreen:

Cheers,
phaetn
Last edited by phaetn on Sat Jan 27, 2018 12:32 pm, edited 5 times in total.
1974 CS1
32/36 DFEV; CompuTronix ign.
9.8:1 c/r; 40/80 intake cam w/ Isky springs
Vicks' SS header & adj. cam pulleys
A/R's progressive coils, Koni Yellow dampers
205/50-15s on CD-66 style rims
Momo wheel, Corbeau seats w/ 5 pt belt
pics and HD vids

zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

Re: A tale of two tire (and wheels)

Postby zachmac » Sat Jan 27, 2018 12:20 pm

The 20mm offset explains the no spacers since I am pretty sure most original wheels were 25mm so yours are actually out a little. That explains the "full" wheels wells as well. I think a set of 15mm spacers with the 35mm offset Team Dynamics would be about right. That would put them right about where yours are. Are you running them with or without the factory spacer plate between the hub and wheel? I think they are about 3mm thick. If I ran a 15mm spacer without them I'd be at about factory offset. (25mm-3mm = 22mm versus 35mm-15mm = 20 mm). If I go back to 15s I'll try that as my rubbing issue is actually the rim inner lip contacting the upper control arm, but just barely (with 2 factory spacers so about 35-6 = 29 offset).
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

DieselSpider
Posts: 2130
Joined: Wed Dec 24, 2014 10:21 pm
Your car is a: 1978 124 Spider with Isuzu Turbo Diesel

Re: A tale of two tire (and wheels)

Postby DieselSpider » Mon Jan 29, 2018 5:05 am

I keep seeing folks posting about replacing tires in 10 years and as a former tire tech and coming from a family who engineered tires and rubber formulations 10 years is not a safe number. Tires age out past reasonable safety limits after 5 years. If you are going with wider 15 inch tires because you want a safer car then you replace them every 5 years since this is Best Safe Practice.

Yes some tire manufacturers do claim 10 years however there is an "IF" which is - "IF" annually starting at the end of year 5 have all the tires dismounted and inspected by a factory tech representing the tire manufacturer. "IF" the factory tech certifies that the tires are still safe then the warranty is extended for another year. When you coun't the cost of the inspections it usually turns out to be more cost effective and ultimately safer to just replace the tires every 5 years.


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