FAQ: Wheel & Tire, Lug, Bolt Pattern, Offset, Center Bore Info

Thanks to Jason, nothincame2mind, and Jelorian.

Wheel/Tire Size Comparer:

http://www.wheelsmaster.com/rt_specs.jsp

or:

http://www.rimsntires.com/specs.jsp

Tire Size Calculators:

http://mcgrefer.com/sizeinfo/
http://www.miata.net/garage/tirecalc.html

Wheel Bolt Pattern Cross Reference:

http://www.roadkillcustoms.com/hot-rods-rat-rods/Wheel-Bolt-Pattern-Cross-Reference-Database.asp

Lug Bolt Pattern Chart (dead link):

http://www.willysoffroadsupply.com/Wheel_Spacer_Chart.html?sid=f816d06972c62f3471cd1bdd3169e9b0

Other links that could be useful?.. please post 'em.

3D Wheel Visualizer (Includes Riviera):

http://www.wheelenvizio.com/?wheel=Envizio

RIVIERA 86-89 14 X 6 5X115 12mmX1.5 70.3
RIVIERA 93-on 15 X 6 5X115 12mmX1.5 70.3
RIVIERA FWD 79-85 15 X 7 5X120.7 12mmX1.5 70

This is real helpful.......Thanks!

AA wrote:

Thanks to Jason and nothincame2mind.

Wheel/Tire Size Comparer:

http://www.wheelsmaster.com/rt_specs.jsp

Tire Size Calculator:

http://www.miata.net/garage/tirecalc.html

Lug Bolt Pattern Chart:

http://www.willysoffroadsupply.com/Wheel_Spacer_Chart.html?sid=f816d06972c62f3471cd1bdd3169e9b0

Other links that could be useful?.. please post 'em.

Do you know what the offset is for the 6.5" wide chrome rims (Riv stock rims)?

Thanks,

dont quote me, but i think it is around +32 offset

Anyone know the offset for the stock 16x7 wheels?
would a +40 make a huge difference from a +30 for example?

i think it is like +32 or +35 depending on wheel.

what are the dimensions to the 1996 stock wheels. what by what

16x7 i believe.

the 8 spokes are 16x6.5 and the 12 spokes are 16x7
all run 225/60/16 tires and have +32 offset i believe
to me the 12 spokes are "stock" since they are the rims specifically for the riv, while the 8 spoke design was offered on other buicks as well. the base wheels are ugly mono wheels with lots of little spokes around the edge, but those were only put on 95/96's with no s/c or other options.

okiedrifter wrote:

RIVIERA 86-89 14 X 6 5X115 12mmX1.5 70.3
RIVIERA 93-on 15 X 6 5X115 12mmX1.5 70.3
RIVIERA FWD 79-85 15 X 7 5X120.7 12mmX1.5 70

The one that says 93-on, is that correct?
Aren't our rims 16 x 6.5 or 16 x 7.0?

jrocha wrote:

okiedrifter wrote:

RIVIERA 86-89 14 X 6 5X115 12mmX1.5 70.3
RIVIERA 93-on 15 X 6 5X115 12mmX1.5 70.3
RIVIERA FWD 79-85 15 X 7 5X120.7 12mmX1.5 70

The one that says 93-on, is that correct?
Aren't our rims 16 x 6.5 or 16 x 7.0?

i dont know why it says 93-on for that size b/c ours (95-99) are 16X6.5 for 8 spoke design, or 16X7 for 12 spoke design still 5x115 bolt pattern.

..I'm pretty sure our bolt pattern is 5x115

With an adaptor, but not with the stock bolt pattern:

Link

Was just trying to verify the specs on the KMC Gnomes I picked up earlier this year, and did some measuring. I found the centerbore is 1/16" bigger diameter than the stock rims, and suspected that was the case when I installed them, they seemed a bit loose. However, the studs and lugnuts seemed to center pretty well when I tightened things up carefully. However, I've found online info that "lug-centric" (as opposed to "hub-centric") wheels need to be torqued down with the tires OFF the ground, to ensure the lugnuts remain exactly centered while torquing. I know I tightened them pretty good off the ground, but had them on the ground for final tightening. I suspect this could be part of my tire road noise issue with these Yokohama tires. Another factor could be that I've been running them on the low side pressure-wise, due to higher wear in the center of the tread prior to my purchase. Lower pressure, means the outside edges wear faster, and I'm thinking that could result in the tire noise from the outside treads as the center section has less pressure on it. Any feedback or comments?

I'm thinking these dual-pattern rims may have been ordered for a non-Riv application that has a slightly larger centerbore. If ordered for a Riviera, there may have been a centering ring added to the wheels. The 2nd bolt pattern is slightly smaller than the Riv's. But I can't find any markings on the rim that indicate what the 2 bolt patterns actually are. It's even possible they could be 114.3mm pattern, with the 2nd being smaller yet. I know a lot of guys run a 114.3 on their 115mm BP cars successfully, but I don't know if you can tell the diff while you're installing them.

You can probably get a centering ring for this, contact KMC to see if they make one. I would suggest using one, I don't like lug-centric rims.

If you find the spec's for our hubs while doing your search could you post them here for future reference. I know our wheel / hub / lug spacing size is 115 mm, but I don't know how the centering rings are measured and sold.
Thanks.

I measured our stock centerbore, but don't recall what it was. Not expecting to pull a wheel anytime soon, unless I remove the RR to snap a pic of the wheelhouse repair.

I'll make a point of contacting KMC before I get around to slapping them back on next spring. I also do not like the centerbore not being correct. What baffles me is that there are no clear markings to indicate what the 2 bolt patterns are on these.

If our bolt pattern isn't 5x115, then what is it? (above link doesn't work).

Has anyone determined for sure what the stock offset is? Is it +32 mm?

I've been going the assumption that the stock pattern and size is; 5 x 115 and +32mm offset.
I believe I've come to that conclusion after having looked up the factory size on multiple sites while looking for aftermarket wheels.
Every site that provides the info has come up with the same size.

99.9% positive our wheels are 5x115.

offset i'm not positive on b/c i believe the different factory wheels have slightly different offsets. +32, +34 sounds about right.

We could guess that the larger wheel (7") would have the smaller +32 mm offset, while the smaller (6.5") would have +34 mm offset. Correct? This would seem to keep the position of the wheels' inside edges (backspace distance) consistent in relationship to the hub. Stock backspace is 5.1-5.2" based on the assumed specs.

I'm looking at Tire Rack's compatible 18" wheel size replacements:

18x7.5"
Offset: 38-45mm
Backspacing: 5.82-6.06"
Bolt Pattern: 5-115
Rec. Tire Size:245/45-18

18x8.0"
Offset: 40-45mm
Backspacing: 6.06-6.29"
Bolt Pattern: 5-115
Rec. Tire Size:245/45-18

18x8.5"
Offset: 35mm
Backspacing: 6.10"
Bolt Pattern: 5-115
Rec. Tire Size: 245/45-18

Aaron, You thinking about getting some 18" wheels ????

I am thinking about auto-crossing this summer, and some lighter, lower profile rims should improve the handling a bit. It grabs fine with the stock rims, but I'm hoping to improve the road feel and reduce unsprung mass. Just looking right now...

I just called a retailer out of Cincinnati called Elites-Wholesale.com - guy's name was Derrick - extremely helpful, with some useful info:

There's a bolt pattern called 5x114.3 (4.5") that will fit our hubs just fine, he says. The holes are typically made with a little slop, so this is good to know when searching for wheels. Most sites like Tire Rack.com will not show the 5x114.3 size as matching the Riviera. Derrick says many newer cars use the 5x114.3 size, so it's a more common wheel choice than 5x115.

This expands wheel compatibility to include the following cars:

Ford Mustang
Ford Crown Vic
Mazda FD RX-7
Mazda Protege5
Mitsubishi 3000GT
Nissan 300ZX
Nissan 350Z
Nissan Altima 2003+
Nissan Maxima
Nissan Quest

More info: Link and complete list of cars: Link

Keep in mind, the above are only compatible regarding bolt pattern, NOT rim thickness or offset. Searching Tire Rack.com or the like under these cars will produce wheels that bolt on the hub, but not necessarily wheels that clear the wheel wells when turning.

Also, he mentioned many of the lower priced rims are made in one of 3 foundries in China. Although the designs are protected under brand names, the quality is about the same. In short, any wheel under $200 or so is probably Chinese made, and of the same quality level as the next brand.