Need Input: Wheel Offset / Spacer Questions

Discussion in 'Discussion Forum' started by lookforjoe, Jan 14, 2020.

  1. lookforjoe

    lookforjoe True Classic

    The new wheels I bought (Rota Kensei) are wider in the rear than the ones I have from Vic's - 9" vs 8", both zero offset.

    I needed 1.5" spacers for the 8" wheels. Before I order new spacers for the wider wheels, to make sure the overall track is the same, I wanted to get others opinions on my math - which sucks in general.

    I am assuming that I need to move the new wheel in by .5" (since they are zero offset) to achieve the same track as I have currently. So, I would need to order 1" spacers to replace the 1.5" I'm using now.

    Does that sound like a reasonable calculation?
  2. carl

    carl True Classic

    I have 8" wide wheels on my X (205/60/13 tires) and didn't need any additional spacers. How about using a stack of stock spacers (doesn't everyone have 10 or more of those laying around) to figure out what size you need?
    lookforjoe and dllubin like this.
  3. lookforjoe

    lookforjoe True Classic

    Like this?


    I didn't think I would need to go that route, car is on jack stands, etc. not easy to raise & lower to check things at the mo :D

    This is what I have from Serpent auto for the Vic's wheels I don't want to remachine these, since I will then be stuck if I want to switch back :)


    I'm going to assume zero offset really means zero offset & get 1" hubcentric spacers with the 4x98 to 4x100 bolt pattern shift for the Rota wheels


    I may end up having to do something with the back brakes to make them pretty like the new fronts

    Dr.Jeff and mkmini like this.
  4. rachaeljf

    rachaeljf True Classic

    Northampton UK
    Track is measured between the wheel centre lines, so moving each wheel in by half an inch will reduce the track by an inch. I guess you want to keep the overall width across the tyres the same, so moving each wheel in by half an inch would be correct if you are also using one inch wider tyres as well. If you are keeping the same size tyres you may not need to change anything.
    Dr.Jeff and lookforjoe like this.
  5. Bobkat

    Bobkat 1979 x1/9

    Calgary Alberta
    I like those wheels! Any shots with more car in them?
  6. rx1900

    rx1900 1981 X1/9

    No, no Hussein !!! If both wheels have the same OFFSET....then your track will remain exactly the same !!! No need to change spacers or anything like that.

    The tread of the tire will be in exactly the same place as before. No further out - or in. No difference there. The only difference will be that the BEADS of the tire will now be spread out a little more. The outside and tread will remain in the same location.
    lookforjoe likes this.
  7. lookforjoe

    lookforjoe True Classic

    Many thanks, Doug. That's why I need help :)

    I'll change the order to match the 1.5" I have now
  8. lookforjoe

    lookforjoe True Classic

    I don't have them installed yet, I will get pics, but it won't be until the spacers are here, they wont fit over the hubcentric flange of the existing spacers
    Bobkat likes this.
  9. mkmini

    mkmini True Classic

    Latvia is good online calculator
  10. rx1900

    rx1900 1981 X1/9

    Hey Hussein. By the way.....please dont tell me you are running those new 9" wheels front and rear....

    And what tires are you putting on the new wheels ?? Sure hope they are a lot wider than the 205 and 225 you were running before.....
  11. artz1731

    artz1731 True Classic

    Denver PA
    Great looking wheels!
  12. kmead

    kmead Old enough to know better

    So if you are trying to maintain where the outside of the rim and the face of the tire is in relationship to the fender lip, then yes a 1/2” thinner spacer will be needed.
    Dr.Jeff likes this.
  13. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    I'm with Karl and Rachael. I believe what Doug said is not what you were asking and therefore incorrect in this case....unless I am the one that is misunderstanding your question.

    The way I interpreted your situation, you wish to maintain the actual location/dimension of the outer lip/edge of the wheels/tires relative to the fenders...i.e. they will look/fit the same overall width (as the old ones) relative to the bodywork. To do that your initial calculation was correct. This is also assuming the wheel manufacturers dimensions are accurate. I've found a large inconsistency between wheel makers when it comes to stated measurements. So you might want to actually get the new wheels in hand and check the true dimensions before ordering any spacers.

    Also remember the inside edge of the wheels will be 1" further inward; .5" due to the wider wheel + .5" due to the narrower spacer. Be sure you have enough suspension clearance for that.
  14. lookforjoe

    lookforjoe True Classic

    UOTE="kmead, post: 337747, member: 204"]So if you are trying to maintain where the outside of the rim and the face of the tire is in relationship to the fender lip, then yes a 1/2” thinner spacer will be needed.[/QUOTE]

    Damn. Yers, that was the point, I got side tracked. I have no room for the wheel to sit further outward. What Doug was saying is that the bead will move out 1/2", with the sidewall stretched compared to the 8" wheel, since I used the same size tire, the only change is the wheel width. I'm not sure now whether it is an issue or not. I've already ordered the spacers. If they are too wide, I'll just machine them down. Can't go the other way & add, so I'll see how it goes.


    there is room for 1" inset - plenty of room by the strut, which is the closest member

    Last edited: Jan 15, 2020
  15. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Rota has some great wheel styles for a small company (relatively speaking when it comes to wheel makers). They seem to focus a lot on variations of vintage designs, which I love - particularly for older car models. These will look great on your modified X. ;)
  16. lookforjoe

    lookforjoe True Classic

    Only 9" in back, fronts are same 8" as existing. Tires are the same

  17. autox19

    autox19 True Classic

    East Lansing, Mi
    Didn't take the jump? 245/40 rears and 225/45 fronts? :)
    Actually, hindsight, i kinda wish i would have went 205s and 225s. Kinda.....


    20180208_180459.jpg 20190313_183959.jpg
    lookforjoe likes this.
  18. Ulix

    Ulix True Classic

    Stuttgart, Germany
    To recap: when using the same size tire on the 8" and 9" rims, the contact patch of the tire will remain in exactly the same position.
    The edge of the rim will stick out further and the side wall of the tire will be shaped differently, will be more "stretched".
    But since it is the contact patch of the tire that is usually relevant to fit and look, I would stick with the same spacers as before.
    rx1900 and lookforjoe like this.
  19. carl

    carl True Classic

    The point with the stacked spacers is you get the actual spacing rather than driving yourself crazy with the math.

    The wheels look beautiful. Just don't weigh your new wheel/tire combo and then compare them to a 185/60/13 tire on an iron cross rim!
  20. Dan Sarandrea (Phila)

    Dan Sarandrea (Phila) Waitin' On Parts...

    Philadelphia, PA
    Not that there is much you can do about it, but I wouldn't want to be a stock rear wheel bearing on a car with significantly wider track + 150% increase in tire patch + 250% increase in horsepower + "spirited" driver.
    kmead and mkmini like this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice