Wheel Fit, offset.
04-07-11, 05:15 PM
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Wheel Fit, offset.
Hello everyone,
I have been looking for a set of 15x7, 4x114.3(bolt pattern) wheels for my 1985 GSL-SE. I have the stock wheels on there now which I believe are 14x7, 4x114.3 and they are fine but I want a set of wheels to just put a set of tires on to race with at SCCA solo 2 events. So, I found a set of Rota RB 15x7, 4x114.3 with a 25mm offset. My Mazda Factory manuel says the stock wheels have a 45mm offset. I did some measurements and I think the Rota wheels will fit but it would be really really close (3mm of space left), I will probably have to roll the fenders. Has anyone put these wheels on a 1st gen or a similar set with the same offset? Or any suggestions for a different set that are the 15x7, 4x114.3?
Thanks you for your help,
VCS
I have been looking for a set of 15x7, 4x114.3(bolt pattern) wheels for my 1985 GSL-SE. I have the stock wheels on there now which I believe are 14x7, 4x114.3 and they are fine but I want a set of wheels to just put a set of tires on to race with at SCCA solo 2 events. So, I found a set of Rota RB 15x7, 4x114.3 with a 25mm offset. My Mazda Factory manuel says the stock wheels have a 45mm offset. I did some measurements and I think the Rota wheels will fit but it would be really really close (3mm of space left), I will probably have to roll the fenders. Has anyone put these wheels on a 1st gen or a similar set with the same offset? Or any suggestions for a different set that are the 15x7, 4x114.3?
Thanks you for your help,
VCS
04-11-11, 03:52 PM
#4
84SE-EGI helpy-helperton
Did you give up?
The stock wheels are 45mm offset, 14x5.5", which is kind of narrow and also why Mazda put 195/60-14 tires on the car. As with anything, unsprung weight, tread width and length, and traction drive a manufacturers choice of tire/wheel, so this one made good sense back in 1984-5.
I have a set of 15x7 wheels with 40mm offset running 205/55-15's and have no issues with rubbing nor rolled fenders - never had a problem with the SE with this setup, and recommend them to anybody looking to go a bit wider. The 40mm offset is only 5mm less than stock - and offset is measured from the centerline of the wheel; and this has the effect of moving the inside edge of the tire slightly further away from the spring on the front suspension - which is where contact will be made with most tire/wheels on the SE. This works to a point that your offset is too low and causes the outside edge of the tires to hit the fenderwell, cutting the tire.
I also ran 205/60-14's on a track car, and once the fenders were rolled - no problems.
I think, based on your wheel sizing, anything with about a 40-45mm offset, tire track width of about 205mm, and aspect ration somewhere around 50-60 should fit fine, work well on an SCCA course, and not hurt performance too much. You might be surprised to find that your stock wheels work better for SCCA Solo II where lighter weight wheels/tires make a bigger difference in braking and acceleration vs. bigger, heavier, wider. Good luck,
The stock wheels are 45mm offset, 14x5.5", which is kind of narrow and also why Mazda put 195/60-14 tires on the car. As with anything, unsprung weight, tread width and length, and traction drive a manufacturers choice of tire/wheel, so this one made good sense back in 1984-5.
I have a set of 15x7 wheels with 40mm offset running 205/55-15's and have no issues with rubbing nor rolled fenders - never had a problem with the SE with this setup, and recommend them to anybody looking to go a bit wider. The 40mm offset is only 5mm less than stock - and offset is measured from the centerline of the wheel; and this has the effect of moving the inside edge of the tire slightly further away from the spring on the front suspension - which is where contact will be made with most tire/wheels on the SE. This works to a point that your offset is too low and causes the outside edge of the tires to hit the fenderwell, cutting the tire.
I also ran 205/60-14's on a track car, and once the fenders were rolled - no problems.
I think, based on your wheel sizing, anything with about a 40-45mm offset, tire track width of about 205mm, and aspect ration somewhere around 50-60 should fit fine, work well on an SCCA course, and not hurt performance too much. You might be surprised to find that your stock wheels work better for SCCA Solo II where lighter weight wheels/tires make a bigger difference in braking and acceleration vs. bigger, heavier, wider. Good luck,
04-17-11, 08:04 PM
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they fit!!!:)
Ok, so i received the Rota Rb wheels(15x7, 4x114 with a +25 offset) in the mail last week along with the Kuhmo Xs tires 205 50 15s and I mounted them on the car and they fit!! 
I rolled the fender lips on all four corners just in case... This weekend I took the car down to the RGR SCCA events sat and sun(outside Farmington NM) and I did not have any problems. Just letting anyone know who is wondering about offsets that fit the 1st gen rx7.
I rolled the fender lips on all four corners just in case... This weekend I took the car down to the RGR SCCA events sat and sun(outside Farmington NM) and I did not have any problems. Just letting anyone know who is wondering about offsets that fit the 1st gen rx7.
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04-19-11, 09:03 AM
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It would be a 5mm difference which would put your wheels 5mm farther out. I do not know if that would work because I calculated my clearance and I only have 3mm of clearance. The wheels by themselves weigh 14.6 lbs. For the SCCA racing I think they work well, but next set of tires I get will probably be 225s.
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