275/60R15 on Stock T Rims? Anyone have pictures?

[Luke]

I really like the idea of fitting the 275/60R15 Mickey Thompson ET Street Radial on My Stock T Wheel. I see a few people on the forum have done this but they don't really mention how they deal with the clearence issues against the frame. Using the 235/60R15 I could barely squeeze my finger between the frame and the rear of the tire.

I have no airbags and stock style suspension with adjustable UCAs and adjustable LCAs. I'd like to avoid notching the frame, if possible. Is there a good size wheel spacer that can be used? Do you need a hub with longer studs to accommodate a larger spacer? I've never really wanted to use spacers. Are they safe to use?

I have a set of Welds I used to use that will fit the 275/60R15 fine but I'd much rather keep those for slicks at track only. They attract too much attention. Around my area, people see a turbo buick with welds and a front mount and automatically think: "9-10 SECOND STREET CAR!"

 

[conn84gn]

Why not go with 255/60R15 DR, I have no rub problems and not as tall as the 275/60R15 DR

 

[turbojd]

Yeah, thats what size tire I am running right now also, P255-60-15 on a 15x7 rim. Nice fit and only 27" tall.

 

[Luke]

I had thought about it...

Why not go with 255/60R15 DR, I have no rub problems and not as tall as the 275/60R15 DR

I was last using the 275/50R15 on my welds. Traction out of the hole was awful (even at low boost) and anything under 20mph was not good at all. The 255/60s had crossed my mind. They'd probably be better than what I have tried but I hear all good things about the 275/60R15 More sidewall to flex and more treadwidth. From What I hear they're good for 1.50 60ft.

 

[turbojd]

I was last using the 275/50R15 on my welds. Traction out of the hole was awful (even at low boost) and anything under 20mph was not good at all. The 255/60s had crossed my mind. They'd probably be better than what I have tried but I hear all good things about the 275/60R15 More sidewall to flex and more treadwidth. From What I hear they're good for 1.50 60ft.

True alot of guys have used the 275-60-15 on a 15x7" stock wheel, I guess it just depends on the brand of tire as to how much side wall flex you would get on a tire that wide on a 15x7" rim. Also the center of the tires would probably wear out quicker with that big of a tire on a 7" wide rim, but if thats no big deal I would just go with the 275-60-15's.

 

[Luke]

Wider Wheel?

True alot of guys have used the 275-60-15 on a 15x7" stock wheel, I guess it just depends on the brand of tire as to how much side wall flex you would get on a tire that wide on a 15x7" rim. Also the center of the tires would probably wear out quicker with that big of a tire on a 7" wide rim, but if thats no big deal I would just go with the 275-60-15's.

I know they make a widened stock T wheel to 8" but doing so increases the Backspace by 1". Wouldn't this create more clearence issuse with the 275/60R15? Is the stock backspace 4" or 4.5"?

 

[Luke]

Wheel Adaptors?

Would wheel adaptors instead of spacers be a good way to solve my problem? I saw a website that says they can be used on race cars and that they're safer than spacers. What do you guys think?

 

[V6POWER]

I run the 255-60/15 MT ET Street drag radials on 15x8 Torque Thrust II wheels. My 60' times are in the 1.5x.

 

[Luke]

That sounds good...

I run the 255-60/15 MT ET Street drag radials on 15x8 Torque Thrust II wheels. My 60' times are in the 1.5x.

How are you launching? That's a good 60'. What Backspace are your Torque Thrust IIs and have you ever tried the 275/60R15?

 

[V6POWER]

I launch at 5# off the foot brake and I believe wheel backspace is 3.5". I don't think the 275 would fit under my car without rubbing the frame.

 

[Luke]

Rubbing with 3.5" BS?

I launch at 5# off the foot brake and I believe wheel backspace is 3.5". I don't think the 275 would fit under my car without rubbing the frame.

Are the 255s really that close to the frame? the 275s are only going to be about a half inch taller all the way around the tire and slightly wider (0.15" on each side). Where do they come close to rubbing and how far do you have? I figured if I had a clearence problem, I'd Shorten up my adjustable LCAs.

 

[V6POWER]

Every car is different as far as how the body sits on the frame. What fits under my car may not fit under yours so my advice to you is to try the size you want and see if it works on your car. I just posted my tire size and my 60' to show that you do not need a 275 to get 1.5x 60'.

 

[Luke]

Mph?

I launch at 5# off the foot brake and I believe wheel backspace is 3.5". I don't think the 275 would fit under my car without rubbing the frame.

Another important factor I was concerned with is MPH. I was crossing the traps at 117 and I think the 28" would benefit me greater than the 27".

 

[V6POWER]

I only run the 1/8 mile here in NC so the 27" works well.

 

[turbo dave]

I have run 275-60-15's on my stock gn wheels- they fit o.k but do rub the frame when turning aggressively- I have aluminum drums as well-still slight rubbing.

 

[Luke]

Drums?

I have run 275-60-15's on my stock gn wheels- they fit o.k but do rub the frame when turning aggressively- I have aluminum drums as well-still slight rubbing.

Thanks for your input. You mention aluminum drums and I never even thought of this as a factor I'm assuming you included that because they may be slightly thicker than the steel drums. Is this true?

 

[nova]

At the bottom of this page My '87 TR pics are a couple pix of the clearance on my TR, using 275/50 15 on stock T wheels and aluminum drums.

 

[BMF_Racing]

Another important factor I was concerned with is MPH. I was crossing the traps at 117 and I think the 28" would benefit me greater than the 27".

with the stock rear end 3.42, what rpm would it drop running 117 to 120 mph going from 26" to 28" ??

anyone have a rpm scale or graph ?

thanks,

Brad

 

[UNGN]

with the stock rear end 3.42, what rpm would it drop running 117 to 120 mph going from 26" to 28" ??

anyone have a rpm scale or graph ?

thanks,

Brad

The RPM drop is roughly proportional to the diameter difference.

26/28 = 93% so your RPM would roughly be 93% of your current RPM at a given speed.

If your RPM is 5400 with 26" tires, it would be (5400 * .93 - roughly 5000 RPM) with 28" tires, so it is a significant difference.

 

[Luke]

with the stock rear end 3.42, what rpm would it drop running 117 to 120 mph going from 26" to 28" ??

anyone have a rpm scale or graph ?

thanks,

Brad

Theoretically...

With the converter locked:
5250 @ 117 to 5350 @ 120 - 26" Tires
4800 @ 117 to 4950 @ 120 - 28" Tires

W/O lockup:
Around 5800 @ 117 to 5950 @ 120 - 26" Tires
Around 5350 @ 117 to 5500 @ 120 - 28" Tires

Use this Top Speed Calculator to determine whats best for your setup. Keep in mind that with a non-lockup transmission such as TH350 or a TH400 to type "Engine Red-line RPM Value" Like this [RPM]*0.9 (ex. 6000*0.9) This won't be exact for your torque converter properties but non-lockup converters should only slip around 10% after stall speed in reached.

Hope this helps.