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Good new about the spacers: it sounds like you're already set. The good news is that there are multiple choices in 17x9.5, and 275/40r17 has lots of tire choices. You could also go with 18x9.5 or 18x10 with a 275/35r18. Are the wheels on there now not something you want to use? Just curious.
Again just curious, does the car not have ABS?
C5 245/17 front 275/18 rear. Like the 5 spoke style but hate the 2 different sizes. I just don't think (mho) that the car was designed for those either. You? I'm going to stick to what I know and go with 17/9.5 and the BFG's
No anti lock its a 1985 Z51. Drivers car Here is the rear tire and wheel. Any info would be great. Thanks again. eta: only thing I wish it had is anti lock not interested in the other controls.
C5 245/17 front 275/18 rear. Like the 5 spoke style but hate the 2 different sizes. I just don't think (mho) that the car was designed for those either. You? I'm going to stick to what I know and go with 17/9.5 and the BFG's
I agree, just stylistically, the stagger diameter doesn't look right on the C4. That look was introduced to minimize the disproportionately large butt of the C5-7, which was brought on by the change to a transaxle architecture. The C4 is classically proportioned and doesn't benefit from that IMO. One option that might be cheaper for you would be to just find two more 18x9.5 like the ones you have, to replace the front 17x8.5. I like the look of these wheels on a C4, just not the staggered diameter.
No anti lock its a 1985 Z51. Drivers car Here is the rear tire and wheel. Any info would be great. Thanks again. eta: only thing I wish it had is anti lock not interested in the other controls.
I keep forgetting the first C4s didn't have ABS. The good news about the later ones is that the traction control can be turned off easily, and the ABS remains.
Last edited by MatthewMiller; 12-19-2018 at 12:05 PM.
C5 245/17 front 275/18 rear. Like the 5 spoke style but hate the 2 different sizes. I just don't think (mho) that the car was designed for those either. You? I'm going to stick to what I know and go with 17/9.5 and the BFG's
No anti lock its a 1985 Z51. Drivers car Here is the rear tire and wheel. Any info would be great. Thanks again. eta: only thing I wish it had is anti lock not interested in the other controls.
Just C5 wheels, nothing special, nothing wrong with running them either.
Just C5 wheels, nothing special, nothing wrong with running them either.
I agree. The local tire store has the BFG A/S I want in the c5 sizes for just under $900. I didn't check with my local tire guy I've used for years but he may be able to get them to me a little cheaper.
If yours is like my 86, here's what I did. I had 16x9.5 38 offset rims and 245x50zr16 tires. Replacements were pretty much BFG's only and some were aged when I checked. I decided to bite the bullet and got some 18x9.5 40 offset rims and 255x40zr18 AS tires. There's a much larger selection, the size and offset fit just like the originals and I'm very happy with the results.
Ok just bought the black/machined 17x9.5x56mm ZR1 knock offs from 1st Rate. Just to make sure I have the right spacers how thick should they be. I can't see them on my other 85 because it has salad shoots.
Ok just bought the black/machined 17x9.5x56mm ZR1 knock offs from 1st Rate. Just to make sure I have the right spacers how thick should they be. I can't see them on my other 85 because it has salad shoots.
TIA
Joe K
Ideally 19mm or 3/4" for most off-the-shelf adapter style spacers. Few actually do more specific specific for adapter style ! I'd think the decision a very 'wise' choice vs the 16" options you were considering.
Ideally 19mm or 3/4" for most off-the-shelf adapter style spacers. Few actually do more specific specific for adapter style ! I'd think the decision a very 'wise' choice vs the 16" options you were considering.
Thanks me too. I"m going all the way. Probably right at the $1500 I really didn't want to spend. Well the plan is to die broke anyway. I was able to sort of measure the spacer on the salad shooter. Looks about 1 1/4. On the Z51 which I can measure with no problem 1 1/2. Yes possible more headaches and money. I just did the math, though I don't know if the formula is correct but 38mm from the 56mm is in inches .70 so that works out. However what I haven't taken into account is the 1 inch wheel with difference of the 9.5 vs wheel well/fender clearance. Maybe the extra .5 to .75 makes up that. Or maybe the spacers handle that. The Irony is I researched everything I need but have no idea what I have. Einstein jr. Thanks for the help obviously I need some and any more will be welcomed.
Thanks me too. I"m going all the way. Probably right at the $1500 I really didn't want to spend. Well the plan is to die broke anyway. I was able to sort of measure the spacer on the salad shooter. Looks about 1 1/4. On the Z51 which I can measure with no problem 1 1/2. Yes possible more headaches and money. I just did the math, though I don't know if the formula is correct but 38mm from the 56mm is in inches .70 so that works out. However what I haven't taken into account is the 1 inch wheel with difference of the 9.5 vs wheel well/fender clearance. Maybe the extra .5 to .75 makes up that. Or maybe the spacers handle that. The Irony is I researched everything I need but have no idea what I have. Einstein jr. Thanks for the help obviously I need some and any more will be welcomed.
To get the new wheels spaced to where the stock 9.5" turbines would have sat in the wheel wells, 19mm or 3/4" spacers will be the ticket. That said, you can try the 1.25" spacers you currently have and see if the wheels still fit without poking out of the fenders too much. I bet they will fit. You've have increased your scrub radius an extra 3/4", but I don't know how much that will actually affect steering feel. As long as the tires aren't hitting anything (try them at full steering lock in both directions), then it won't hurt to try it. If you decide to back it down to 3/4", you have lost nothing but time.
To get the new wheels spaced to where the stock 9.5" turbines would have sat in the wheel wells, 19mm or 3/4" spacers will be the ticket. That said, you can try the 1.25" spacers you currently have and see if the wheels still fit without poking out of the fenders too much. I bet they will fit. You've have increased your scrub radius an extra 3/4", but I don't know how much that will actually affect steering feel. As long as the tires aren't hitting anything (try them at full steering lock in both directions), then it won't hurt to try it. If you decide to back it down to 3/4", you have lost nothing but time.
I'm going with what is on there now the 1.5 Here's a pick of the current setup. If I get fitment like this it will suit me.
Front is sort of an optical illusion. It's fitting very similar to the rear. If the new ones fit like that using the spacers I already have I will be happy.
Again I thank you and everyone for all of their help. If I have anymore questions you know I will ask. I can't wait to see the final results.
Last edited by Joe K; 12-22-2018 at 10:05 AM.
Reason: ocd typo corrections
I'm going with what is on there now the 1.25. Here's a pick of the current setup. If I get fitment like this it will suit me....Again I thank you and everyone for all of their help. If I have anymore questions you know I will ask. I can't wait to see the final results.
Ok just bought the black/machined 17x9.5x56mm ZR1 knock offs from 1st Rate. Just to make sure I have the right spacers how thick should they be. I can't see them on my other 85 because it has salad shoots.
TIA
Joe K
The recommended adapter thickness for this wheel on an early c4(84-87) is 3/4" to put back to the factory position. I would recommend 1" adapters ideal for a few reasons. (a)1" are easy to get.(b) 1" is a stronger built part because you get 1/4" more metal on the adapter (3/4 adapters are pretty thin). (c)The wheels and tires actually look better sticking out another 1/4".
The recommended adapter thickness for this wheel on an early c4(84-87) is 3/4" to put back to the factory position. I would recommend 1" adapters...
I just want to clarify the difference between adapters and spacers. Spacers are literally just rings with holes that fit over the existing wheel studs and space the wheels out further. Longer-than-stock studs may be required to provide enough threads for safe lug nut torque, but otherwise they are fine to use and are only stressed in compression/clamping and in shear (which will never be an issue regarding their strength). Adapters actually bolt down to the hubs with the original wheel studs by themselves, and they then have their own wheel studs onto which the wheels and lug nuts are mounted. They are subject to stress risers at the holes where they are torqued to the hubs, and at their own studs where the wheels bolt to them. They have ten total points of stress, half of which have force going toward the hubs and the other half of which have force pulling toward the wheel, but they also have shorter studs that are then able to withstand more torque before stretching. The solution for the latter issue when using spacers is to install long ARP studs and be done with it. I don't want to start a debate about which is better. I just wanted to clarify the difference, because the OP said he's using spacers and not adapters. And for 3/4" or 1", that's what I'd use too.
So with that said:
[1" adapters are] ideal for a few reasons. (a)1" are easy to get.(b) 1" is a stronger built part because you get 1/4" more metal on the adapter (3/4 adapters are pretty thin). (c)The wheels and tires actually look better sticking out another 1/4".
a) I don't know, you may be right about either adapters or spacers being easier to get at 1" thickness.
b) thicker adapters are indeed stronger, for the reason you gave; but for spacers it doesn't matter except that thicker means more tension stress on the lugs.
c) I agree, as long as they aren't poking out of the fenders. That's part of why I suggested he start with the spacers he has now and see how it fits and looks.
Last edited by MatthewMiller; 12-22-2018 at 01:50 PM.
I always assume most people know the difference between spacers and adapters. I probably should not make assumptions like that. As far as spacers go, I would never consider using anything larger than 1/2" and only with longer studs. The 1" adapter, 56mm combo on early cars has been used multiple times on this forum and others and looks great.
Did a test fit and found out that I have adapters not spacers. Not a problem for me. May protrude from the fender more than I expected but I will go with it, for a while anyway. Tires get mounted Wednesday. Right at $700. Here's a shot of the test fit. I'll post the end results when I get them put on.
Did a test fit and found out that I have adapters not spacers. Not a problem for me. May protrude from the fender more than I expected but I will go with it, for a while anyway. Tires get mounted Wednesday. Right at $700. Here's a shot of the test fit. I'll post the end results when I get them put on.
I bet they won't poke out at all with the car on the ground and the suspension at normal ride height.
I hope not but I did some quick measurements and the old and new just don't match. I'm just overthinking again.
If it's still on the jack - just put a 'straight edge' vertically on the rim edge!! I was surprised you didn't actually confirm/mention the adapter thickness. You've mentioned 1 1/4 and also 1 1/2 I believe. If the C5 was an OE 8.5 and you confirm the offset from the back-side simple math tells you just where you'll find the 'rim edge' vs an original fit. Wheel/tire fitment ain't nothing but simple math.
*** As many times as you're going to mount tires/wheels and not knowing how many times it was done previously I'd consider 'pinning' the studs/bolts in the adapters. It's very easy to spin the stud/bolt in the adapter. That creates an issue that you certainly don't want to experience.
*** I'd also confirm that there's a 'center bore' dimension on the adapter and if there is measure it. Very inexpensive adapters don't have. You'd like to see 70.3 for a dimension.
The adapter is 1.5". I did an eyeball measurement. I took the tape measure from the back of the wheel where it mounts and eyeballed the rim on both. The new rims just looked wider. Very unscientific. And on the center bore when I looked at adapters I saw something about wheel centric, hub centric and what have you. That's when I decided that what I had was going to be good enough until I had the time to find out. I didn't take the adapter off and the only markings I could see were bolt pattern.
12-19-2018, 10:51 AM
Here is the rear tire and wheel. Any info would be great. Thanks again. eta: only thing I wish it had is anti lock not interested in the other controls.
I was able to sort of measure the spacer on the salad shooter. Looks about 1 1/4. On the Z51 which I can measure with no problem 1 1/2. Yes possible more headaches and money. I just did the math, though I don't know if the formula is correct but 38mm from the 56mm is in inches .70 so that works out. However what I haven't taken into account is the 1 inch wheel with difference of the 9.5 vs wheel well/fender clearance. Maybe the extra .5 to .75 makes up that. Or maybe the spacers handle that. The Irony is I researched everything I need but have no idea what I have. Einstein jr. 
