Plus Sizing is a fairly recent trend (I think it started in the late 80’s or early 90’s). Well when I say recent, I mean compared to the 50’s and 60’s when I was getting into cars and making them street cool. The basic idea of Plus Sizing is to replace the stock wheel size with a larger diameter wheel and still maintain the same original tire and wheel combination diameter. Back in the early days, up to and including the 70’s, the only thing that happened when you put larger diameter tires on your rod, was the speedometer read slower than you were actually going. That only worked when you said “but Dad, the speedometer said I was only going 50”.

In today’s world, when you change the wheel and tire combination diameter, it effects a number of things with your ride. Not only will it change the speedo reading, but the ABS braking system, the engine management system and with some cars the suspension control system. Computers don’t take kindly to changes of input components.

So to make sure you don’t alter the input from the wheel and tire combination, the diameter of the OEM combination needs to be maintained. To accomplish this you need to understand the meaning of Plus Sizing. A simple definition is to take the original wheel diameter and plus up from there. A Plus 1 conversion is upping the diameter of the original size by 1 inch (i.e. 14″ to 15″). In some extremes I’ve heard of a Plus 9 conversion (i.e. 17″ to 26″). That’s a bit radical for me, but to each his own. Most tire and wheel dealers are very aware of the Plus Sizing concept and can guide you as to the proper tire size to fit your wheel diameter choice and maintain the original tire and wheel combination diameter. It’s pretty difficult to get the exact match, but if you are within 5% you’re okay.

Start Your Wheel and Tire Package Search Now

Year:

Make:

Model:

Loading…

Now let’s discuss the Pro’s and Con’s of Plus Sizing.

The Pro’s – First of all, you’ll be cool if you Plus Size. The bigger the diameter, the cooler you are (at least some folks think so). The biggest benefit from Plus Sizing is the increased road handling. By increasing the wheel diameter (and maintaining the original overall diameter), the height of the tire side wall deceases. This has the effect of less tire sway or roll, and increases the stability or cornering ability of your ride. Other than those 2 attributes, I’m hard pressed to come up with more Pro’s.

The Con’s – The first thing that comes to mind is the loss of suspension. By deceasing the side wall of the tire, you will increase the effect of road bumps, pot holes, expansion joints and all the other deformities of our roads and highways. Road noise will be increased also. In addition to the loss of ride comfort, you will also experience a loss of free time. I come to this conclusion based on the theory that the bigger the wheel, the more time it requires to keep it shining. Another Con is the tire mounting folks that have to put these tires on these wheels (20″ and up) aren’t real thrilled with the whole concept.

A few things to beware of when choosing to Plus Size. The larger the diameter of the wheel, the more difficult it is to meet the load requirements for a safe and reliable wheel. Some manufacturers solve the problem by adding material to the wheel so it will pass the performance standards (see TECH Stuff 3). By adding material, the weight of the wheel becomes heavier than the suspension the vehicle is designed to take and function properly. The tire and wheel are considered unsprung weight, and can cause excessive wear on the struts or shocks, bearings, spindles and brake systems.

Plus Sizing is not a bad thing when done properly.

Share This Page

Search for Wheels and Tires by Vehicle:

Year:
Make:
Model:
Loading...

43 Responses to The Pros and Cons of Plus Sizing

  1. HI I HAVE A 2016 LEXUS ES350 IT HAS 225X45X18 OEM WHEEL MY SUMMER CROME WHEELS AR 18” X 8.5 CAN I GO TO 245X45X18 SIDEWALL HEIGHT IS THE ISSUE I THINK THANKS FOR YOUR HELP LEROY

    • Leroy, we don’t list 18×8.5 as working on your vehicle, sounds like it’s working for you. Our system recommends between 7 and 8″ width for 18″ rims, our fittings are fairly conservative so that rubbing is not an issue. The largest 18″ we recommend is 8″. For a 18×8 you can go up to 235/45-18.

  2. I noticed on just plus tire sizing you don’t list a 245/40/18

    https://www.performanceplustire.com/search-by-vehicle/2017/bmw/3-series-f30/

    I have a 2017 BMW 330i Xdrive and I am happy with the factory 18” x 8” wheels squared set-up
    I was going to replace the 225/45/18 with 245/40/18 and 245/45/18 is to tall
    245mm is the widest you can put on an 8” rim, not to mention rubbing issues if you tried to go wider on the front? And I’d have to replace all the wheels
    There won’t be much difference in looks, probably unnoticeable
    Would there be much benefit to braking handling
    I know the diameter is a little lower, so the car might launch faster, but use more gas? Lower the gear ratio?
    And the 245/40/18 is 1 pound heavier adding to the rotational and unsprung weight
    Diameter 25.72 vs. 25.97 = 0.25 = 1/4″ less
    Width 245mm vs. 225mm 20mm = 3/4″more
    So I was thinking 3/4″ wider x 4 wheels is 3″ more contact patch on the pavement?
    I know the numbers are section width and not tread width, but are probably proportional Sidewall for ride/handling trade-off
    Sidewall 3.86 vs. 3.99 = 0.13 = 1/8″ less
    Speedometer will read 62.8 mph at 60 mph
    Cost difference is negligible
    Is the difference so small, you wouldn’t even know the difference?

    Thank You

  3. Hello, my family recently bought a toyota tacoma that was plus-sized, came with some big tires. When you look at the wheel space and the rubber wall, they are about an inch or less away from each other. Would you say that since the space is small, it can cause the wheels to rub against the walls and cause the truck to brake on its own? This happened while making a sharp turn on some curvy roads while going downhill. Thanks!

  4. I want to move to a 265/50R20 inplace of the 255/50R20’s that come OD on the 2018 VW Atlas RLine. Any issues?

  5. 20 inch rims 255 30 20 for a 2007 volk’s jetta.

    What else should I upgrade on the car to get the most out of the ride with 20in rims.

  6. Have a question I have a 330i and took my car in to get tires a year ago now they are worn and took in again and they informed me they put on the wrong size the front size was put on the rear too does this have an effect on the performance of my car? And they are the specialist that screwed up and want me to bear the expense of replacing the tires after 10,000 miles.

  7. Greetings I am looking at going to a little larger Tire I currently have 265 r65 17 are there any disadvantages to going to a 265 70 17 looks like it will increase my height by about half an inch what about speedometer and gas mileage

  8. It sure got me when you said that it is a lot easier to navigate the road and that it offers more control if the wheel that the person is using is plus sized. I think the same thing applies to wagon wheels, especially if the landscaping is pretty wide and has some rough areas. Since my brother’s wagon that he uses for the vegetables need a new set of wheels, I think he needs to choose ones that are bigger in order to make it easier for him.

  9. My son has a 2016 Infiniti q70 5.6L.
    it came with 18 inch tiires. he says it handles poorly and he needs 20 inch tires. i have no idea what to get him. any recommendations? …and will he need new wheels? he wants rims in black with white trim…does that exist?
    thank you

  10. My 2018 Silverado came with the 17” rim/tire but wanta buy similar chrome 20”s that we’re avail when bought. Was the 20” suspension different from my 17” truck ? Maybe a lift kit? Thankyou craig

  11. Hi,

    I have a 2014 F150 XLT… I Currently have BFG all terrain T/A KO2 – Size 275/65 R18.

    I’m installing new very soon… I Would be installing the same brand but this in this size 265/70 -R18. Could this make a difference that’s bad, or be bad overall for the vehicle?

    Thanks for your reply in advance.

  12. I was accidentally given the wrong size tires today right before the tire shop closed. I didn’t notice until they had all left. The wrong size was put on the front of my car. It’s a 2015 Mercedes C300 4matic sport. It had stock run flats on it front 225/40 r 19 and rear 255/35 r 19. They replaced the front tires with 245/40 r19. It looks like it’s going to rub. Is this going to be an issue or not? They used crosswind brand

  13. I was accidentally given the wrong size tires on the front of my car. It’s a 2015 Mercedes C300 4matic sport. It had on it front 225/40 r 19 and read 255/35 r 19. They replaced the front tires with 245/40 r19. It looks like it’s going to rub. Is this going to be an issue or not?

  14. I have a 2012 Ford F-250 with the 6.7L diesel. The truck came with 18” wheels and tires. I want to put 20” wheels and tires (like what Ford puts on some of their F-250 diesels). Will this hurt anything since some of the diesel trucks like mine come with 20”? Thank you for your help!

  15. I drive a genesis g80 5.0 on 19 inch tires. I really want to upgrade to 21’s but I’m nervous about the ride quality. I figure 20’s won’t be that big of a difference but 22’s would definitely defeat the purpose of having a luxury car due to the poor ride quality. Could 21’s be the solution?

  16. I have a 2018 F150 2WD and plan on putting a 2″ level on the front end. I currently have 275/55R20’s, but would like to upgrade to 285/60R20’s. I have been told that can’t go higher then 275 because I would need modification from the tires rubbing. Could you please give me your input on this.

    Thank you!

  17. My truck has a stock tire size of 235/75/15. I currently have 30×9.5×15 on it, which is about a size up. I want to go to a 31×10.5×15, which would be about 2 sizes up. The biggest difference in specs (sidewall) is still within the 15% (1 inch) recommended oversize for trucks.

    Diameter is 7.3% (2.1″) more.
    Width – 13.6% (1.26″) more.
    Circumference – 7.3% (6.6″) more.
    Tire weight – 17% (8lbs) more.

    Other than throwing off the speed-o more, would I be making anything wear out prematurely? Would ABS still function properly?

  18. I’m thinking of plus sizing the wheels of my dodge charger SXT 2018 from 215 65r17x7 to 245 45R20x8.5. Will appreciate your thoughts on this? If i do, is there an impact to my mileage?

    Thank you so much

  19. I am buying a 2019 RDX with Advanced Pkg and SH-AWD. I would like to add 20″ wheels. Can those fit on the tires that come with the OEM?

  20. I have a 2007 Mazda B2300 pickup. I have a cap on the back that has shelves and holds tools and handyman stuff. The back sags down a little. The factory size is 15″ rims. Would adding an inch better protect the suspension or whatever is affected by the fact that my trtuck sags down in the back? Would adding an inch not affect the speedometer and brakes too much, if just an inch?

  21. I have a 2007 Z71 Tahoe (all factory) and it feels very top heavy when on interstate at 70+ mph. According to your article, if I go from 17’s to 20’s it will help this but I may have some other issues that you stated. Correct?

  22. I kept 20 inch stock rims, but the tires I just put on are considerably taller. My only worry is that it may tear up my transmission. Will it be ok, or no.

  23. I want a taller tire on my 17 inch wheel,I
    Have
    A2009 Honda accordEXL LARGEST ENGINE,
    What’s the max size tire II can use without hitting Wheel when turning

  24. Hello, I have a ‘17 Toyota Corolla SE that came factory 21545R17, & I’d like to plus size the wheels from 17-18.
    Should I, which tire would you recommend for best all around performance(summer & all season) & size? I’m wavering between Bridgestone & Michelin, but open to all.
    Also, would a performance chip aid the computer in modifying the changes of going from 17” to 18”?
    Thank you

  25. My 216 ATS sedan all-wheel has 18” and I hate the 40 profile (rim to close to the road), it now has run-flats. Ahh! Can I get away with 45, perhaps even 50’s?

Leave a Reply

Your email address will not be published. Required fields are marked *

Feedback Form
How are we doing?