# Tire Size/Rim Size Question. **URL:** \ **Category:** PittSpeed Automotive\ **Created:** [March 19, 2007, 1:29pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697 "2007-03-19T13:29:12Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Bravada\_442](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/bravada_442/32/5982_2.png) [@Bravada\_442](https://forums.speedlife.net/u/Bravada_442)\ **Post date:** [March 19, 2007, 1:29pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/1 "2007-03-19T13:29:12Z")
So I’m looking to run a 7" wide wheel on my 06 Impala (they are the factory SS wheels). I want to run a 245 width tire. I’m pretty sure when running a 245 they suggest running it on a 7.5" or wider rim, but I’m not 100% sure. Will I be okay running that wider tire on that size rim? The factory size that chevy puts on those rims is a 235/50/18, but that is a little too large for the non-SS suspension that my Impala LT has. ---
**Author:** ![SoLow](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/solow/32/6001_2.png) [@SoLow](https://forums.speedlife.net/u/SoLow)\ **Post date:** [March 19, 2007, 4:37pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/2 "2007-03-19T16:37:46Z")
u should be fine on that…i had a 255/50/16 on my stock zq8 rims ---
**Author:** ![Pewter](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pewter/32/5936_2.png) [@Pewter](https://forums.speedlife.net/u/Pewter)\ **Post date:** [March 19, 2007, 4:40pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/3 "2007-03-19T16:40:19Z")
> [@\*\*\*\*\*Official: Mighty Meet Thread\*\*\*\*\*](https://forums.speedlife.net/t/official-mighty-meet-thread/10918/1847): > > u should be fine on that… x2 ---
**Author:** ![Shaggy](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/shaggy/32/5945_2.png) [@Shaggy](https://forums.speedlife.net/u/Shaggy)\ **Post date:** [March 19, 2007, 5:12pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/4 "2007-03-19T17:12:06Z")
x3 I ran 245-50-16 on 16x7 Pony wheels for years ---
**Author:** ![KeithO](https://avatars.discourse-cdn.com/v4/letter/k/4bbf92/32.png) [@KeithO](https://forums.speedlife.net/u/KeithO)\ **Post date:** [March 20, 2007, 2:23am UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/5 "2007-03-20T02:23:02Z")
What can and cannot safely be used on a given wheel width is heavily influenced by tire width but it is not the final word. Sidewall construction and strength plays a role in this as well (Load Rating is an indication of sidewall strength). I don’t think you can say absolutely whether or not a given size will fit without consulting the manufacturer’s specifications. Go here: [http://www.tirerack.com/](http://www.tirerack.com/) The drill down through the “products” link to a given brand of tire that you are considering. For an example, I drilled down through BFG Goodrich g-Force T/A KDW. When you get to the main page for the particular tire, click on the “Specs” link. Inside there you will see the full specification for that particular tire. There they say that the rim width range is 7.5"-9" for 245/45 ZR17 tires. I wouldn’t recommend these. However, if you go to the specification page of the Continental ContiSportContact 2, you will find the rim width range is 7"-9". Note that there are multiple models in this size of this tire. The one with the correct rim width is the one with the 95Y load rating. I would recommend these because they are “approved” by the manufacturer… Could tires outside the manufacturers’ specifications work? Yeah, probably. But you might have problems and have no one to bitch at if you go outside the specs. Hope this helps. ---
**Author:** ![marks\_lude](https://avatars.discourse-cdn.com/v4/letter/m/f17d59/32.png) [@marks\_lude](https://forums.speedlife.net/u/marks_lude)\ **Post date:** [March 20, 2007, 5:13am UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/6 "2007-03-20T05:13:23Z")
i think you be fine. i race with 225 width on my stock 6.5" wide rims. you might get reduced contact patch however from bending in the sides of the tires just a bit. this usually isnt as much as an issue with street tires however. an interesting find by a guy who road races a prelude on my other forum. heres the text sans pictures: "Now, here’s the interesting part. Stack two tires on top of one another. One stack is the 15x8 Rotas and the other stack is the 15x7 Koseis both with identical 225/45/15 Hoosier race tires. Notice a difference? 😉 What is the difference? The Kosei stack came in right at 18 3/4". The Rota stack came in just a hair under 19 3/4", say it’s 19 11/16". That’s a whopping 15/16" of an inch increase in OA width just from changing from a 7" wide rim to an 8" wide rim!! Almost a full inch! That’s only two tires, if you compare 4 tires, you get 1 7/8" wider rubber overall. I couldn’t believe it, but it’s about inline with the rule of thumb that section width increases on average 0.2" per 1/2" of rim width" ---
**Author:** ![scoob8000](https://avatars.discourse-cdn.com/v4/letter/s/e8c25b/32.png) [@scoob8000](https://forums.speedlife.net/u/scoob8000)\ **Post date:** [March 21, 2007, 12:33pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/7 "2007-03-21T12:33:35Z")
KeithO’s right, check out the specific tire you’re looking for on Tirerack. You’ll find the ideal rim width for that tire, as well as a range of what the manu says can be safely mounted… ---
**Author:** ![Bravada\_442](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/bravada_442/32/5982_2.png) [@Bravada\_442](https://forums.speedlife.net/u/Bravada_442)\ **Post date:** [March 21, 2007, 1:43pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/8 "2007-03-21T13:43:54Z")
> [@i have to poop](https://forums.speedlife.net/t/i-have-to-poop/28927/15): > > KeithO’s right, check out the specific tire you’re looking for on Tirerack. You’ll find the ideal rim width for that tire, as well as a range of what the manu says can be safely mounted… I did. I, for instance, decided to look up a 235/45/18 to see what it would be like. A goodyear in that size only would “work” on a 7.5 to 9, but a 235/50/18 would work on anywhere from 6.5 to 8.5 How can 5% of sidewall make an INCH difference in how the tire will fit? That just seems stupid to me. ---
**Author:** ![imported\_Sleeper](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/imported_sleeper/32/5939_2.png) [@imported\_Sleeper](https://forums.speedlife.net/u/imported_Sleeper)\ **Post date:** [March 21, 2007, 1:45pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/9 "2007-03-21T13:45:18Z")
Ur good man,i run 245/50/16’s on mine with absolutley no problems and mine are they same size as yours. ---
**Author:** ![KeithO](https://avatars.discourse-cdn.com/v4/letter/k/4bbf92/32.png) [@KeithO](https://forums.speedlife.net/u/KeithO)\ **Post date:** [March 21, 2007, 3:00pm UTC](https://forums.speedlife.net/t/tire-size-rim-size-question/188697/10 "2007-03-21T15:00:33Z")
> [@Airflow through a grill for a fmic, need answers](https://forums.speedlife.net/t/airflow-through-a-grill-for-a-fmic-need-answers/28926/15): > > How can 5% of sidewall make an INCH difference in how the tire will fit? That just seems stupid to me. It’s not just the height but the aspect ratio plus the thickness and materials used in the sidewall itself. The way I look at it is that I will go with the manufacturer’s spec on things like this - I’m sure the tire manufacturer’s legal department had a say in what they considered safe and have these specs to avoid lawsuits and warranty issues.