Official Wheel/Tire/Wheelbolt Guide

This Tread should be made into a "Sticky". Thanks, Robbie, for taking the initiative on this important topic.

 

Early (1995) F355 wheels use a 22mm Hill Engineering insert.
Later (1996-) F355 wheels use a 23mm Hill Engineering insert.

 

Here is what I figured out in kilogramm:

OEM Front 7.5 x 18 22 lbs., 1.1 oz. 10,010 kg
OEM Rear 10 x 18 23 lbs., 7.6 oz. 14,743 kg

Challenge Front 8 x 18 19 lbs., 6.6 oz. 8,82 kg
Challenge Rear 10 x 18 20 lbs., 11.4 oz. 9,403 kg

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With Pirelli slicks from 1995:

Challenge 245 Slick front = 19,1 kg according to my scale
Challenge 305 Slick Rear = 19,9 kg according to my scale

just the rims

Challenge Felge Front = 8,8 kg according to my scale
Challenge Felge Rear = 9,6 kg according to my scale

(balanced by 45 gramm lead per rim)


Part #226245 hopefully fits to the CH wheels too, right?


cinque

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1 g = 0,0354 ounce
1 kg = 2,203 ounce
1 t = 1,103 tons 1 ounce (oz) = 28,35 g
1 pound = 16 (oz) = 0,454 kg
1 ton = 907 kg

 

OEM 355-GTS,GTB,Spider(Taken from year models 97 & 99):

Hub Thread Depth 11MM

OEM Cast Iron Rotor Hat Thickness 9MM

(This means the lug bolt projection from backside of wheel mounting pad should be a minimum of 20MM, with ideal at approx. 21MM)

Stock OEM Lug Bolt Projection from Mounting Pad 21MM(un-torqued)

(NOTE:If your aluminum inserts have extreme wear from numerous lug bolt over torque, there will be minor variations in lug bolt projection-this will show up as a +)

 

Measurements taken from a 98 355 F1 GTB

Factory wheel 18x7.5 offset 46.15
Bolt pattern 5x108

A. Mounting surface to first obstruction frame side 225mm
B. Mounting surface to first inside fender 60mm
C. Hub Diameter 67.1mm
D. Diameter: Center to top of Caliper (x2) 180mm
E. Protrusion of Caliper past mounting surface 30mm
F. Hub Length 10mm
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Measurements taken from a 98 355 F1 GTB

Factory wheel 18x10 offset 77.9
Bolt pattern 5x108

A. Mounting surface to first obstruction frame side 270mm
B. Mounting surface to first inside fender 55mm
C. Hub Diameter 67.1mm
D. Diameter: Center to top of Caliper (x2) 185mm
E. Protrusion of Caliper past mounting surface 11mm
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Brake Hat Thickness for Various 355 Brake Systems:

OEM Stock Cast Iron Rotor Hat-9 MM

CH Factory Aluminum Hat-8 MM

BREMBO GT Aluminum Hat-8 MM

 

Does anyone have a picture of a Stock Five Spoke 355 Wheel, without a tire on it showing the "bead" of the wheel?

 

Can I fit tire sizes 295/30/18 rear and 235/35/18 fronts on factory wheels. I spoke to Tire Rack and they said no. The tires are 265/40/18 rear and 225/40/18 front. F355 Spider

 

A 355 stock OEM lug bolt(52MM), installed(un-torqued) on a 355CH wheel has a projection from wheel mounting pad, of 18.5-18.6MM.

To safely secure a 355CH wheel to a non-CH 355 with stock braking system, a 55MM lug bolt is a MUST....in other words DO NOT USE the original 52MM lug bolt!!!!

NOTE:I would strongly suggest that you double check these measurements for the CH wheels you have, as some teams might have machined the wheel mounting pad and the aluminum inserts. If these modifications were done,especially reducing the wheel mounting pad thickness, a shorter bolt can be used. Remember that you need atleast a 20MM and ideally a 21MM lug bolt projection to get correct thread contact on the hub.

 

Many of the 355 wheels had the inner rubber rings go missing somewhere in their life. This led to trapped moisture between the Mag wheel and the steel rotor and then the resulting galvanic corrosion. MANY of the 355 wheels were machined at the mounting pad area when the contact surface got down to 50% which resulted in more lug bolt protrusion. Also created a problem in the wheel centering area on the hub with many showing a great deal of corrosion. The normal amount machined was in the range of .125" but if one is ordering all new lug bolts this would be something to inspect. I have seen a good deal more than the .125" machined off some of the race wheels. I suspect you should also find a "Norm" measurement for the mounting pad thickness so long as this effort is being made.

 

I sent out most when there was a tire chance in progress. Only done on the wheels where the contact patch was greatly compromised from corrosion. Due to the amount I saw removed on some race wheels I suspect it occured when wheels were being repaired / straightened after a shunt.

 

Bruce wanted to see what a Challege wheeel lug looked like since I couldn't PM him(how come we can't) a pic I'm stickin' it here. So there ya go Bruce not the best photos but they will have to do.
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Many thanks Vern. Those pic's tell me alot...great!!!!

I'll be over this weekend to rake leaves and paint the porch..lol