Clearance between tire and spring seat

mbuskuhl

mbuskuhl

New member
I put on some new wheels and have exactly 1/4" clearance between the tire and front spring seat. I don't think this is enough for comfort or flex/suspension travel, what is the minimum distance you'd like to see?

The car is a 2nd Gen RX7, 225/50 tires, 15 x 7 + 35 wheels, currently 3/8" spacer which gives me the 1/4" clearance. I was going to go to a 1/2" spacer or stack a 3/8" and 1/4" to get 5/8", either I way I need to buy more spacers. How much clearance do I need for comfort before I buy some new spacers?
 
I put a square of tire crayon on the inside sidewall and if it rubs off, it's too close. If it doesn't it's OK. :)

K
 
I put on some new wheels and have exactly 1/4" clearance between the tire and front spring seat. I don't think this is enough for comfort or flex/suspension travel, what is the minimum distance you'd like to see?

The car is a 2nd Gen RX7, 225/50 tires, 15 x 7 + 35 wheels, currently 3/8" spacer which gives me the 1/4" clearance. I was going to go to a 1/2" spacer or stack a 3/8" and 1/4" to get 5/8", either I way I need to buy more spacers. How much clearance do I need for comfort before I buy some new spacers?
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Run the 1/2 inch spacer (never stack if possible) and you get about 3/8 clearance with that combination. That tire will move a ton under cornering. You are running 2.5" springs? Is the perch too big or just to the edge of the spring?
 
I did the tire crayon this past weekend with some 15 x 6.5 + 40 and a stacked 3/8" and 1/4" spacers to get me by - no rubbing. Now that my new wheels are in and on the car I'm trying to get the right spacers and the good high quality ones. I will definately do tire crayon again next track time to verify.

I'm going to pickup 1/2" spacers now, that should give me at least 3/8"clearance. I am running a 2.5" spring and got all of my suspension from Flatout motorsports. The car recently had a setup done by the MX-5 cup points leader Saini, it handles good so I don't think anything is screwy with the suspension. I was able to "roll" a regular pencil (not move freely) between the tire and spring seat, the pencil measured .28" with a micrometer.

I just thought of this, maybe my wheels are not +35? I ordered them from Team Dynamics and that's what they had in stock. It doesn't say the offset though on the box or the wheel - they are the Pro Race 1. I did order and they did tell me they are +35... not sure how to actually verify.
 
Checking the clearance with the crayon should show what is happening but with most roadracing tires, the sidewalls are so stiff that you should not see too much deflection.

I just started using some 225/45-13s on my CRX and only have 3/8" clearance in the rear but have had no issues.

Make sure you have enough lug length for the wheel spacers also!!
 
I just thought of this, maybe my wheels are not +35? I ordered them from Team Dynamics and that's what they had in stock. It doesn't say the offset though on the box or the wheel - they are the Pro Race 1. I did order and they did tell me they are +35... not sure how to actually verify.
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You'll ahve to do a quick search to find what +35 equals I don't know off the top of my head. My +38 is 4 inches of back space. Take a flat edge across the back of the WHEEL. Then measure from the bottom of the straight edge to the back fo the wheel that sits against the hub.
 
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