Measuring Wheel offset and Wheel Spacers with pictures - By Anthony Hyde Update 8/2009

How To MEASURE WHEEL OFFSET (in detail) - written by myself: (I have included real figures). Example based on tire/tyre 225 wide (nominal 225/45/16)
- Remove a wheel, and lay the outside face of the wheel flat on the ground. (So now your looking at the inside wheel mount face)
- Place a flat piece of material thats wider than the tire/tyre on top of tire. Carefully measure from the ground the overall height (or width) of your tyre & rim package = eg. 226 mm high.
Then divide your answer by 2 = 113 mm (this gives you the centre line of the rim and tyre)
- Place a ruler though the middle of the rim and measure from 'ground to wheel mount face' = eg. 92.5
- Subtract 113-92.5 = 20.5 mm. This is your wheel offset.
Most rims are positive offset these days, the mount flange being way out near the outside of the wheel. - From rim centre line, 'a positive offset' is when the mount flange is toward the outer edge of rim.

More advanced double check method - You have measured the overall width of rim or wheel, eg 226. To check your math, your after the two figures from your wheel that will combine & add up to 226.
Your previous << Place a ruler though the middle of the rim and measure from 'the ground to wheel mount face' = eg. 92.5 >> Now do from top of wheel down to the mount flange eg 133.5. CHECK 92.5 + 133.5 = 226 overall width.
If your figures don't add up to the overall width, then keep checking all 3 figures till they do. It can be agony but ultimately you will understand your wheel perfectly.
Offset check - Once your above figures add up, you will get the same offset answer using either dimension, Eg. 226/2=113 centre line of rim.
Now 113-92.5 = 20.5 mm being the same as 133.5-113= 20.5 mm offset.



Volvo talk: Volvo rims have positive offsets (100,200,700,900,850 onwards). Many standard Volvo 240 rims have a 20 mm positive offset. This is good for the front, but for the rear when fitting wider rims this offset needs to be reduced by adding a spacer, otherwise the wheel will rub on the inner guard. Further down the page is a list of Volvo wheel offsets and wheel PCD.
Reportably, widening the 'rear track' on a 240 Volvo by using a set of rear spacers gives a 2 to 3 g handling improvement on a skidpan.

Whatever your wide wheel width, try and keep at least 25 mm or 1" clearance on inner tire/tyre to inner guard.

Examples of spacer thicknesses to achieve a wider track:

RIM DIMENSION

TIRE / TYRE SIZE

OPTIMIZED SPACER THICKNESS

FINAL OFFSET

Standard 15" rim offset 20 mm

R-Sport 20 mm or ~ 25/32"

20 - 20 = 0 mm

16 X 7 with std rim offset 20 mm

225 / 50 /16

8 mm or 5/16"

20 - 8 = 12 mm


LONGER WHEEL STUDS - Notes: On a 240 with Volvo spec rims, if fitting spacers over 5 mm thick, longer wheel studs are definitely required - always check for full thread for the wheel nut.
The genuine 240 Volvo & SAM extended wheel bolts (studs) are available individually - Part # 8360085. The length of the genuine Volvo long studs is a usable 50mm (2") out from the hub. The total stud length is 66 mm. Volvo and SAM can also supply a (expensive) factory 240 Spacer Kit # 8360083 that includes two x 20 mm thick rear Al.Alloy wheel spacers, plus 10 extended wheel bolts and longer attachment screws. As required, the alloy spacers can be machined thinner. The weight of a factory spacer is 871 grams each, being heavy as they are near aircraft grade alloy.
For the 740, the SAM longer stud is # 9508764 . Nearly all large Volvos use the 5 x 108 PCD stud pattern even on the newest models.

240 wheel stud thread is 1/2"x 20 TPI UNF. The only 17" Volvo wheel designed for the Volvo 200/700 series where the Polaris, PN 3529717. A most attractive 17x7" five spoke wheel with a 20mm offset. Wide wheels are best utilized in low offset configurations so wider tires don't rub the inner rear fender.


 

Wheel Lip Roller Tool - New and trendy solution - There available in the shops these days. Or call the Tire Rack, 1-888-981-3952, and rent their professional Wheel Lip Roller Tool - fast, cheap and high quality results (pics, thanks Alvo, USA)


Pic A

Different Types of wheel spacer:

Standard Offset Rims: See Pic A

- Reasons for wheel spacers: to move a wider rim away from the inside arch (thus to reduce rim offset); and / or to obtain a slightly wider wheel track for enhanced cornering stability. Most Volvo 240/740 alloy Rims have a offset of 20 mm.
- Method: Longer genuine Volvo wheel studs # 8360085 combined with a spacer of thickness between 5 and 20 mm.
The spacer Pic A is both hub and stud centric. Spacer attaches to hub with one M6 screw as per Volvo rear standard. Front 240 hubs have two attachment screw holes.

Important note: Ensure spacers have a big countersunk / chamfer / counterbore / relief on each stud hole. This is to clear the base diameter of the wheel stud, as its a lot larger than the thread, and to ensure wheel nuts torque up properly.
The spacer must sit dead flat against the hub - check for this.


PIC B (Pic by Alvaro Gil)

Large Offset Rims: See Pic B (850 type onto a 240/740)
Reasons for wheel spacers: 850 rim offset is 43 +mm, so at least a 30 mm spacer is req'd to suit a 240/740. On a 240 with T-5R rims,a reader says 15mm spacer on the front works. (real offset 43-15=28mm)

Pic B shows a large offset adaptor. Stage 1 bolts up to the existing hub using wheel nuts.
Stage 2 - uses the new wheel studs pressed in from the back to attach to new rims.
Commercial units are available and are listed on this webpage. An alternative is to track down a precision machinist to make the spacer, as both lathe and milling machines are required. Custom made spacers offer the chance to change the Stage 2 PCD (pitch circle diameter) dimensions to suit a more popular rim. Using a milling machine with a dividing head attached to the bed, the centre bore must be clocked up exactly before the pitch circle diameters are slot drilled or twist drilled through. Both sets of PCD holes should be drilled (or at least pilot drilled) in the same setup, otherwise the rim will never run concentric with the axle/spacer, no matter how well the wheel is balanced.

ADAPTOR Kits - front& rear ADAPTS 850 wheels onto 200/700/900

FURTHER READING and Selection: H&R Wheel Spacers in USA.
Typical Volvo Wheel Offsets & VOLVO WHEEL PCD (not all model variants are listed)

100-series : 5 holes x 108mm pitch circle diameter, 40mm offset. - Up to 1974
100-series : 5 holes x 108mm, 25mm offset - 1975-
200-series : 5 holes x 108mm, 20mm offset.
Wide alloy rims up to 7-8" will fit with this offset on the front, but adding a rear spacer will prevent any inner-guard rubbing when going up kerbs at a big angle.
700-series : 5 holes x 108mm, 25mm offset. -
700 series rims usually fit 200-series but not vice versa due to different brake caliper/ larger disc diameter. The 16"x7 (Gemini) and 17" rims fit OK. Most 205/55/16 tyres will be fine on a 240 if your suspension is in good condition, though rubbing on the rear may occur occasionally. Most 17" rims use wider tires and hence inner guard rear rubbing becomes more likely, so add a rear spacer.
900-series to 1992 : 5 holes x 108mm, 25mm offset
960 / S90 / V90 and 850 series 1992-1993: 5*108, 43mm offset
900-series 1994 onwards : 5 holes x 108mm, 43mm offset
850-series and V70--I : 5 holes x 108mm, 43mm offset - 1994 on
S80-series T6 : 5 holes x 108mm with 35mm offset, 17 x 7
V70--II, S60--I , S80-series : 5 holes x 108mm 49mm offset


Technical Article
Wheel Track, Brakes and Rims - by Anthony Hyde 15 /1/2008 - Featured in 'The NSW Volvo Club' newsletter (Sydney, Australia)

This months technical musings touches the subject of Wheel Track, Brakes and Rims.

Wheel Track is the width between the front wheels verses the width between rear wheels. Note this is different from 'wheelbase' being the distance from front to rear wheel centres. Wheel track dimension depends on the width of rim / tyre fitted, as a standard narrow steel rim will have alter the maths compared to a wide alloy rim. A reason for looking deeper into this is a 240 front brake upgrade and hence rim clearance.

The 240's have a rather odd Track width, the front being far wider than the rear, so when viewed from behind it's very noticeable, and if one didn't know any better you might conclude the chassis has taken a whack. Keen car club members eyes are drawn to cars with dents and chassis alignment issues.

The Volvo 240 Track width (with alloy rims) is typically:
Front 1420 mm and Rear 1350. That's 70 mm difference or a very noticeable 35 mm per side.
No wonder R-Sport offered 20 mm per side wheel spacers (the rears are still 15mm inboard)!

By comparison :
Volvo 142 - track width is both 1350 mm Front and Rear, so dead even.
Volvo 740 Turbo - track width is 1460 mm on both Front and Rear, so even. Other 740s are within 10 mm of this, so at worst a 5 mm difference either side.

A Victorian Volvo club fellow, Ash Davies, worked out that Mazda RX7 Turbo II brake callipers can be adapted without drama to the 240. I've had the parts on the work bench for detailed investigation. The RX7 calliper is of similar design to the Volvo being a 4 piston design, and being made from Al.Alloy its 1.8 kg lighter than the Volvo cast iron calipers. The brake disc is from a 740 Volvo 1988-95 being 23.4 mm bigger in outside diameter so offering more leverage.

But, the RX7 Turbo II brake callipers are a bit wider by about 6 mm, and placed further out on the 740 disc, so the typical Volvo 15"x6 242GT / GLE Virgo rims don't fit.

Volvo 16" rims (Gemini 5 spoke 740/240) fit but need a 6.4 mm spacer, so freak me out, the front track would be even further out per side 35+6 = 41 mm. The wheel alignment guy would laugh trying to set up his laser beam(s). Rear spacers are then a must fit.

This leads to considering custom rims, like a 3 piece design. This way a rim can be made so they don't need spacers, will clear the brakes, and the rim will sit where a standard one does thus avoiding tyre scrub issues. Guards need flaring out a bit though.

Wheel Track, Brakes and Rims - they all need to be considered as the 240 front to rear Track is rather odd compared to other Volvo models.


Back to Quick Technical Index OR Back to 240 Sports Handling Article

Updated 8/2009 AH.