Tire width / spacer question
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Instructor
Joined: Jun 2001
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Tire width / spacer question
I currently have 20mm spacers up front with 205/50/17 tires. The fenders have been rolled, so clearance isn't a problem, but there isn't much to spare.
I am replacing the tires with 225/45/17s, which probably won't fit with the current spacers. My question for the honorable gurus out there is this:
1) Should the 20mm spacers be replaced with 10mm?
2) Are 10mm spacers available?
On the rear, I am replacing the 255/40/17 (with 15mm spacers) with 265/40/17s. Clearance issues are similar to the front.
3) Should the 20mm spacers be replaced with 15mm?
TIA for your answers.
I am replacing the tires with 225/45/17s, which probably won't fit with the current spacers. My question for the honorable gurus out there is this:
1) Should the 20mm spacers be replaced with 10mm?
2) Are 10mm spacers available?
On the rear, I am replacing the 255/40/17 (with 15mm spacers) with 265/40/17s. Clearance issues are similar to the front.
3) Should the 20mm spacers be replaced with 15mm?
TIA for your answers.
Last edited by D.G..; Dec 2, 2004 at 02:32 AM.
Thread Starter
Instructor
Joined: Jun 2001
Posts: 127
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Dan,
The car is a '95 Cab (narrow body) with std. 17" cup wheels. The spacers serve two purposes. First, to eliminate the ugly gap between the fender and the tire when the car is lowered (which in my case is ROW-M030 height), and second, to widen the wheel base which improves the lateral stability, although the amount is probably negligible. This is the standard setup performed by S-Car-Go racing in San Rafael, CA. Included in the package is a set of modified ROW sway bars that eliminate the under steer and compensate for any weird affects the wider wheelbase might introduce. The setup is quite neutral with the standard tires.
Since the new front tires will be 20mm wider than the existing tires, it seems to follow that they should extend out 10mm farther on each side. So by reducing the spacers by 10mm, the outer edge of the tires should be in the same place as before. At least that is my thinking.
The car is a '95 Cab (narrow body) with std. 17" cup wheels. The spacers serve two purposes. First, to eliminate the ugly gap between the fender and the tire when the car is lowered (which in my case is ROW-M030 height), and second, to widen the wheel base which improves the lateral stability, although the amount is probably negligible. This is the standard setup performed by S-Car-Go racing in San Rafael, CA. Included in the package is a set of modified ROW sway bars that eliminate the under steer and compensate for any weird affects the wider wheelbase might introduce. The setup is quite neutral with the standard tires.
Since the new front tires will be 20mm wider than the existing tires, it seems to follow that they should extend out 10mm farther on each side. So by reducing the spacers by 10mm, the outer edge of the tires should be in the same place as before. At least that is my thinking.
Last edited by D.G..; Dec 2, 2004 at 02:33 AM.
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Joined: May 2001
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From: St. Louis
Dave
I've always been leery of the use of spacers for other than correcting geometry/wheel placement to factory specs. Maybe we'll get some knowledgeable opinions on that point.
Although the "lateral stability" rationale for the spacers seems strained, if you like the visual difference, that's good enough reason for your setup.
Your theory seems sound for slimmer spacers assuming theoretical tire dimensions. In practice, those dimensions vary among tire makes & models. It would be prudent to get real dimensions for the specific tires you'll use if your tire/fender clearances are tight. Most of the manufacturers' websites have those measurements.
Your front change retains about the same diameter & should increase oversteer from your reported neutral handling. The rear change will increase dia by about 1/3" & the added width should bring you back towards neutral. W/o the spacers I know you'd have no front clearance issues & doubt you'd have any in the rear.
I've always been leery of the use of spacers for other than correcting geometry/wheel placement to factory specs. Maybe we'll get some knowledgeable opinions on that point.
Although the "lateral stability" rationale for the spacers seems strained, if you like the visual difference, that's good enough reason for your setup.
Your theory seems sound for slimmer spacers assuming theoretical tire dimensions. In practice, those dimensions vary among tire makes & models. It would be prudent to get real dimensions for the specific tires you'll use if your tire/fender clearances are tight. Most of the manufacturers' websites have those measurements.
Your front change retains about the same diameter & should increase oversteer from your reported neutral handling. The rear change will increase dia by about 1/3" & the added width should bring you back towards neutral. W/o the spacers I know you'd have no front clearance issues & doubt you'd have any in the rear.
Track Day
Joined: Jul 2001
Posts: 18
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From: No. CA
Dan,
Your point about the variation among tire makes and models is well taken. Before I remove the old tires from the wheels I will take some baseline measurements.
What I plan to do is to lay a straight edge across the tire and measure the distance from the straight edge to the rim, and also to the edge of the tread. I will repeat the measurements after the new tires have been mounted. The actual difference in tire width will be easy to calculate from the results.
I will probably have the tire shop remove the spacers for the drive home, and will mount the new spacers later.
-dave-
Your point about the variation among tire makes and models is well taken. Before I remove the old tires from the wheels I will take some baseline measurements.
What I plan to do is to lay a straight edge across the tire and measure the distance from the straight edge to the rim, and also to the edge of the tread. I will repeat the measurements after the new tires have been mounted. The actual difference in tire width will be easy to calculate from the results.
I will probably have the tire shop remove the spacers for the drive home, and will mount the new spacers later.
-dave-